It sounds like the Start Menu folder has been modified in a way which is actually fairly common among malware these days.
Check out this guide: http://www.bleepingcomputer.com/forums/topic405109.html
There are several tools mentioned in the guide. The first, unhide.exe
, removes the "Hidden" attribute of all non-system files and attempts to restore your Start Menu.
If unhide.exe can't restore the Start menu, then you'll want to download and use one of the Start Menu reset tools near the end of the guide; only use the one listed for your specific operating system. These reset tools won't fix everything, obviously, but they will restore the default Start menu.
Edited by Andrew, 31 January 2012 - 01:39 PM.