I'm having a very similar problem to you, and was wondering if you fixed it? If so can you share? My problem started when trying to save a project in windows movie maker (5.1) for the first time. I selected "save as" and WMM crashed. This happened again when I restarted WMM and tried to "save as." It also happened when I tried to "browse" for files to upload to YouTube in both Firefox 2.0 and IE6. I restarted my computer, and it happened again when I tried to attach an excel document to an email in Thunderbird. Each time the program froze and had to be closed by using ctrl+alt+del. The same activity on all 3 programs leads me to believe it's a problem with windows itself, probably the file explorer. Please help! Thanks