Hi, I had the same problem. Disabling the shell extensions for 3rd party programs helps, especially Adobe Reader. Use ShellExview to do this on the admin account.
The complete resolution is to disable Windows Search service (use services.msc), and also change the registry settings for Superfetch. The registry path is
HKLM\system\currentcontrolset\session manager\memory management\prefetchparameters. Change the
EnableSuperfetch key to 0. Don't stop the Superfetch service (I think it is necessary for Prefetch to work). Reboot. Give it 24 hours to sort itself out as you use the PC. Mine is as fast as before but without the explorer hangs and crashes. Probably because the system is doing what you want when you want, and no longer updating the search index and stuffing the RAM full of anticipated programs....
Install
Locate32 to replace Search - very very fast searching, but not for file content, but suits me fine.

Richard Happy Vet