Visual studio and Vista offline files

Hello,

I'm starting to use the offline file feature as a way to keep a backup
of all my data on a share. I'm moving some Visual Studio projects to a
share.
The problem is that now, when I build I get a lot of errors
error PRJ0008 : Could not delete file 'XXX'
Make sure that the file is not open by another process and is not
write-protected.

The strange thing is that the file XXX doesn't exist (at least that's
what the explorer and "dir" say). The problem appears only when
working offline with the Offline Files feature.

Is this a known issue?
Thanks,
Vincent