project looks modified but no files shown when synchronizing

Hi,
I have a few projects in Eclipse that look as a file under them is
modified.. (you know.. that small star in the icon of the project).
However, if I go to Team -> Synchronize with Repository it shows me no
changes.
 Some of my projects have this problem, some don't... so probably it's
 something from my projects, but I can't figure what.
 
 Do you know what could be the problem ?
 
 Sorry if this question has been already answered, but I searched for it
and couldn't find it.
 Also, this message was posted on subclipse-issues list initially - I thought that's where I should post it - but now I duplicated here also.