Hi

1. Boot into safe mode with "networking" and go to Trend Micro Housecall and let it run.

2. Download Stinger from McAfee and let it run.



explorer - explorer.exe - Process Information
Process File: explorer or explorer.exe
Process Name: trojan.w32.Codered

Description:
explorer.exe is a process which is registered as a trojan. This Trojan allows attackers to access your computer from remote locations, stealing passwords, Internet banking and personal data. It is a registered security risk and should be removed immediately.
Processes

Virus Precaution:
The original file from Microsoft gets placed at C:WINDOWSSystem32explorer.exe . if you find it anywhere else then you should be suspicious for sure.



Luck..
Additional Info...


Edit: you could if you have the CD's Uninstall Norton, disconnect from the net and see how the pc responds, see if explorer.exe is maxing out again, if not then possibly Norton is the reason (IMHO usually is)..Norton Uninstall Tool