Note that Switch.pm is a source filter an as such notorious unreliable. I remember a discussion in the CB a while ago where quantum had some code on his scratchpad that had a mysterios error. The script included a subroutine, that wasn't called. The strange thing: When you commented it out the error went away.

Three or four monks (including me) who worked on the code could only scratch their heads. Then virtualsue pointed out the script used Switch.pm. Removing the use Switch; statement fixed the problem.

From the docs of Switch:

There are undoubtedly serious bugs lurking somewhere in code this funky :-)

Update: Corion told me quantum's name. I had forgotten it.