Scala 2.8.0 problems on Windows 7

I installed scala 2.8.0 last night and I seem to be having some issues getting it running. If I type scala at the command prompt it comes up with the following:

> scala
Exception in thread "main"开发者_开发问答 java.lang.NoSuchMethodError: scala.collection.mutable.ListBuffer.toList()Lscala/collection/immutable/List;
        at scala.collection.TraversableOnce$class.toList(TraversableOnce.scala:399)
        at scala.collection.mutable.ArrayOps.toList(ArrayOps.scala:34)
        at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:33)
        at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

Anyone have any ideas? I'm on Windows 7 professional, with Oracle JRE 1.6.0_21

Did you set the SCALA_HOME environment variable to point to the correct directory?

Did you have an older version installed? If that's still on your path then it may be causing problems...

EDIT

Can you paste the contents of your PATH and CLASSPATH environment variables? Perhaps using pastie or pastebin if they're on the large side.

You should also update to Java 1.6.0_22 if at all possible, due to this bug which was present in update 21: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6969236

Turns out this problem occurred because I put the sbt-launch.jar in the lib directory for my scala installation. Once I moved it into another directory scala worked fine.