Help!! My computer lost it's start bar,etc

Hello,

I use Windows XP.. Came home one day and was not able to connect to internet.. I did all the usual troubleshooting.. The next day I lost my start bar.. ipconfig/renew says the rpc server is unavailable.. Cannot open my firewall cause it says option to start ics service.. Won't allow me that there.. Tried the system restore but it didn't offer me a date of when to go back.. explorer.exe didn't bring back the start bar... Computer started acting funky for a week.. Then popups were jumping out while not in a browser...

Any help would be appreciated!!

Thanks,
Brian