List((1, 2), (3, 4)).exists(_._1 > 2) will run once, but not twice in the REPL.
The second time causes the compiler to complain that "This entry seems to have slain the compiler"

The same thing happens for Vectors and ListBuffer-s (I haven't tried any other collections). Mixing collections has the same effect (that is, if I do this with a list and then a vector, the vector attempt crashes, and vice versa).
Changing the test the second time (to, say, _._2 > 0) results in the same crash.

This works correctly when compiled. Other people on #scala report they don't have this problem, although I'm not sure what version/OS etc. they are using.

The REPL prints a typical Java style infinite error message:

java.lang.AssertionError: assertion failed: List(value _1$mcI$sp, value _1$mcI$sp)
at scala.reflect.internal.Symbols$Symbol.suchThat(Symbols.scala:1916)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.matchingSymbolInPrefix$1(SpecializeTypes.scala:1460)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transformSelect$1(SpecializeTypes.scala:1483)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1579)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1347)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.transform(TypingTransformers.scala:44)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1712)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transformSelect$1(SpecializeTypes.scala:1467)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1579)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transformSelect$1(SpecializeTypes.scala:1467)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1579)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1347)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.transform(TypingTransformers.scala:44)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1712)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.internal.Trees$$anonfun$itransform$2.apply(Trees.scala:1363)
at scala.reflect.internal.Trees$$anonfun$itransform$2.apply(Trees.scala:1361)
at scala.reflect.api.Trees$Transformer.atOwner(Trees.scala:2600)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:30)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:25)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:17)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1360)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.transform(TypingTransformers.scala:44)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1692)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.api.Trees$Transformer$$anonfun$transformTrees$1.apply(Trees.scala:2559)
at scala.reflect.api.Trees$Transformer$$anonfun$transformTrees$1.apply(Trees.scala:2559)
at scala.collection.immutable.List.loop$1(List.scala:173)
at scala.collection.immutable.List.mapConserve(List.scala:189)
at scala.reflect.api.Trees$Transformer.transformTrees(Trees.scala:2559)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transformTemplate$1$1.apply(SpecializeTypes.scala:1599)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transformTemplate$1$1.apply(SpecializeTypes.scala:1599)
at scala.reflect.api.Trees$Transformer.atOwner(Trees.scala:2600)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:30)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transformTemplate$1(SpecializeTypes.scala:1599)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1601)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.api.Trees$Transformer.transformTemplate(Trees.scala:2563)
at scala.reflect.internal.Trees$$anonfun$itransform$4.apply(Trees.scala:1408)
at scala.reflect.internal.Trees$$anonfun$itransform$4.apply(Trees.scala:1407)
at scala.reflect.api.Trees$Transformer.atOwner(Trees.scala:2600)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:30)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:25)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.atOwner(TypingTransformers.scala:17)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1406)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.internal.SymbolTable.itransform(SymbolTable.scala:16)
at scala.reflect.api.Trees$Transformer.transform(Trees.scala:2555)
at scala.tools.nsc.transform.TypingTransformers$TypingTransformer.transform(TypingTransformers.scala:44)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform1(SpecializeTypes.scala:1712)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2$$anonfun$transform$3.apply(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.reportError(SpecializeTypes.scala:1420)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1428)
at scala.tools.nsc.transform.SpecializeTypes$$anon$2.transform(SpecializeTypes.scala:1371)
at scala.reflect.api.Trees$Transformer$$anonfun$transformStats$1.apply(Trees.scala:2589)
at scala.reflect.api.Trees$Transformer$$anonfun$transformStats$1.apply(Trees.scala:2587)
at scala.collection.immutable.List.loop$1(List.scala:173)
at scala.collection.immutable.List.mapConserve(List.scala:189)
at scala.reflect.api.Trees$Transformer.transformStats(Trees.scala:2587)
at scala.reflect.internal.Trees$class.itransform(Trees.scala:1366)

and on for many more lines