Lets run this quick programme first to see if I can restore the start menu
Download RogueKiller to your desktop
[*]Quit all running programs
[*]For Vista/Seven, right click → run as administrator, for XP simply run RogueKiller.exe
[*]When prompted, type 6 and validate
[]The RKreport.txt shall be generated next to the executable.
[]If the program is blocked, do not hesitate to try several times. If it really does not work (it could happen), rename it to winlogon.exe
Please post the contents of the RKreport.txt in your next Reply.
Once you are happy I will remove my tools and the quarantined malware for you