OK. I'm in Firefox, I click a Megaupload link to download a video. While I'm downloading, I open a window to look at another video in the same folder I'm downloading to. As soon as I open the folder, "Explorer.exe has made an illegal operation and will be closed. Send bug report?" I click "Don't send", then all folder windows plus the start bar disappear, then the system automatically restarts the process. This will always happen.