there was a post about this problem less than a week ago, he repeared the problem with a system restore, if i remember correctly, the cause was "cccleaner", it cleaned out his registry, and for some reason also his recent list on the start menu.
maybe you also used the above program, or something similar.
like i mentioned on the other post, i have a registry hack, but i never used it on windows 7, only vista, it worked great over there,but it required a restart.