I have a weird issue with Scala IDE 4.1 useScopesCompiler and -Ybackend:GenBCode that result in compile errors; I observed that disabling/enabling useScopesCompiler with -Ybackend:GenBCode cause spurious compile errors.

Here are the steps to reproduce the issue:

1. Freshly Install and launch Scala IDE 4.1 with a fresh workspace
2. Add -Ybackend:GenBCode in the Scala compiler preference
3. Import the attached Team Project Set File
4. Disable useScopesCompiler (this triggers recompilation)
5. Enable useScopesCompiler (this triggers another recompilation)

After Step 5, some of the imported projects have compile errors (sometimes the compile errors also happen in Step 4); no amount of project cleaning help to rid of the errors.
To remove them, I have to (temporarily) take out -Ybackend:GenBCode, which then triggered another recompilation.
I can then add back -Ybackend:GenBCode without causing the compile errors to appear.
If I do Step 4 and 5 again, the errors reappear.