Designer 7 files corrupted

I'm an old user of Designer 7 and I have a lot of files created with it.

I work on Windows XP and since a few days I have a big problem...

When I try to load a file (*.dsf), the file is loaded but if I save it I never can't reload it. Then each time I try to load it I receive an I/O error disk message... The problem is the same for all of my files "*.dsf" !!!

Of course, I try to uninstall and reinstall Designer but the problem stay the same ....

Is there somebody to help me please.

Thanks