Unity regenerates GUID's for assets

Hello, I'm using unity with SVN with my team and for everyone it works just fine, for me, it keeps regenerating some of the GUIDs for some files, an entire directory of assets called 'models' containing fbx files and a few more file out side of that folder. I've setup the work with svn according to instruction by unity's site and i've added the correct file to svn ignore list. I tried to delete the entire folder and i've tried to delete Unity's cache and reimport the entire project.

Anyone has an idea what can cause this?

Thanks