r279 - C2 doesn't have access to save folder anymore

After updating to the last version, C2 displays that message when I try to save or export file :

I tried to revert to older version, clean registry and backup system, it keeps stop me from saving my projects, any solution to this problem? Thanks

EDIT : I can save in is the Download folder and the User folder, but that's all

Solved by going back to r275, keeps happening as long as I use r277 or r279