Nani,
Probably not a lot of help to you, but I had the same message appear just this morning (first time ever).
It didn't appear for all forms - just one out of about 10 that I had checked out under SourceSafe.
Repair + Compact didnt help so I bit the bullet and, after checking in all my other changes (I didnt try to check in the duff one just in case), recreated my Access database from SourceSafe - losing my changes to that particular form but enabling me to get back into it.
Shep