User Shortcuts Dissapeared

I have been using Vista Ultimate for a while now and have had no problems at
all with it.
Two days ago, 70-80% of my Start Menu program shortcuts dissapeared. I did
some digging and found out that the *All users* shortcuts are there, but all
my *user* shortcuts were gone.
I had to go into Program Files/*program* and make the shortcuts again, one
by one, and move them back to the menu.
Is there a reason for that to happen? I never messed up with User Accs or
anything. And all my documents and music and videos didn't dissapear. I did
not install any programs either.

Thank you.

Rafael