I believe that you may have a corrupt path bound into your project files
now.  If it is in the cached build results, a clean build all should fix
it.  If it is, on the other hand, in the file paths, there is no easy
way to fix it.  Among the difficult ways that might work, try looking
through the files for windowsisms, try bringing up the project
properties and looking for windowsisms, and finally, regenerate from
scratch.

<soapbox>
This is why I really, really wish that Eclipse had a pure text project
file format that it could import from and export to.  Storing in that
format would be better still, but that is likely a harder sell.

XML would be a natural choice, but anything that would let us archive
and then understand our project files without needing to work in the
Eclipse environment would make me happy.

It would make our lives easier, and thus increase Eclipse adoption in
our group, if we could generate an eclipse workspace with a few hundred
dependent projects from a passel of xml or text files.  We could then
generate those from our CM system during our nightly build process,
without needing Eclipse on the build machines.
</soapbox>

Scott