Start-up problem

Yesterday, my internet connetion "froze"...Vista seemed to be working properly, but I couldn't access the internet. The Internet Connection wizard indicated that my internet connnection was fine. I rebooted, and when Vista booted up it said "Preparing Desktop"...it never said that before. When it fully booted, my entire desktop was gone except for the recycle bin (and the Start button changed appearance to look like the old XP start button). All the TSRs failed to launch, including Norton. I also can't access the internet from any program. I can get to anything I have saved on my hard drive...all applications, etc. I tried to do a system restore, but clicking on the link doesn't do anything at all.

I have Vista Home Premium and a Dell Vostro laptop. Haven't had any problems previously.