Explorer using 100% of CPU time in WinXP

Last Sunday I started working on some wedding video editing and transfer to DVD for a friend. Right after I finished rendering the first 1.5Gig MPEG I noticed Windows Explorer using 100% of the CPU resources for a minute or more when I opened the directory with the large file.

I started playing around and found that all my folders with large AVI or MPEG files caused this problem. The problem was especially bad in one folder that has an 18Gig AVI capture file.

Searching around the net for information on this problem I found a number of forums with people having the same problem. The information led me to a Microsoft Knowledge base article with details about the problem. The culprit is Shmedia.dll analyzing the file contents to let Explorer display media specific information about the file. The Microsoft article states that the problem was fixed in SP2 but, since my PC is fully patched I think the problem has come back. Also the article says the problem is only with AVI files but I was seeing it with MPEG files as well.

There are a few different solutions posted around the net for the AVI problem. Looking at the various solutions I chose to use the CLSID renaming method as detailed at pc-speed-up.com.

As I expected, renaming the CLSID to:


fixed the problem with AVI files but did not help with the MPEG files.

I looked in the registry to find out what CLSID provided the hook to Shmedia.dll for MPEG files. I found that

HKEY_CLASSES_ROOT CLSID{c5a40261-cd64-4ccf-84cb-c394da41d590}

is the key for MPEG’s. I renamed the key to:


and it fixed the problem for MPEG’s. I hope this helps someone else having this very frustrating Windows problem.

WARNING – manually editing the registry is extremely dangerous if you are not careful you may have to re-install windows to get the PC working again. You have been warned so, don’t complain to me if you screw up your PC by following my information.