Explorer.exe cpu usage

Hope someone can help here!
I have been have a problem occasionally with explorer.exe using up most of the CPU keeping it at a continously high usage level. I have found the knowledge base information about it on the Microsoft web site and to say it is less than helpful is an understatement their suggestion was to ensure I have the lastest release. My have windows XP SP1 and it is set to automatically update when a new critical update is released I double checked last night and it is up to date. Anyone have any ideas why explorer.exe does this I have seen some comments on trojans or worms causing it but my virus software and firewall would hopefully stop them, and have not found any on the hard drives?
Microsofts knowledge base seems to indicate that an update to SP1a would fix it but SP1 should be the seem with some copyright issue software (VM)

Any suggestions would be have helpful

 

How high is the usage, and at those times what programs are running? Does the machine slow-up?

Have you run SpyBot and Ad-Aware?

 

When it does happen it the usage ranges from 79% to 100% for a few hours unless I reboot. Tends to happen when I move large video files from one drive to the other or try to delete the same sort of files from the C: drive. Have run spy bot and ad aware they found a few things which are now gone from the system.

 

Download this edit from Kellys-Korner. AVI Search Remove (Line 74)

See if that helps. If not, download Process Explorer and use it to locate the problem. Very likely an AVI codec.

 

thanks I will give it a go and let you know