Cannot use Windows Explorer on Windows 2000

I am running Windows 2000. I have made no outside changes to my OS, but now I am unable to access any of my desktop icons. I cannot use explorer to open any directories on my computer. I cannot get to the control panel by using Start > Settings. I cannot use Explorer as a web browser. I am currently using Netscape. All else seems to be fine. It seems to be specifcally a problem with explorer. I am running Explorer 6. I downloaded it again and reinstalled Explorer from the Microsoft Website. I have reinstalled Windows 2000. I have not reformatted and done a clean install - would like to avoid that option if possible. My virus protection (Symantec) is up to date and I have no viruses.

Anybody?