Explorer.exe problems

Hi guys I am having major issuies, My start menu has gone as well as my desktop icons, if i run explorer.exe from task manager both will appear for about 10 seconds then go again, I cant get to anything in my c: because it dissappears staright away. What is causing explorer.exe to crash all the time?? I have run multiple virus checks and have got nothing

Thanks For Your Help

Sabby