Hi. I've undertaken the task of fixing the PC of a friend of a friend of mine, and basically, there is just one problem. One of the users works perfectly, as though nothing was wrong. Logging into any of the other three (not including a fourth which I added in order to test if the same problem was happening with new users) gives nothing but the desktop background. Pressing CTRL+ALT+DEL gives the task manager. From there you can run anything that doesn't require explorer.exe to run. (Such as itself, control.exe, iexplore.exe and so on.) That includes explorer.exe. Trying to run explorer.exe gives a flash of the taskbar, which immediately disappears, i.e. explorer.exe quits immediately. I've tried doing a google search about it, and I've tried searching this forum, but to no avail. I've also tried doing the things I could think of, such as a system restore (failed, for some reason...) and running "sfc /scannow", which completed, but didn't help much. The event logs don't give any useful information, and I'm basically stumped. They claim it happened after their computer automatically updated Windows Media Player 10, but I think this is just a coincidence. I tried rolling back (uninstalling WMP 10 with Add/Remove programs) without it helping anything. If anyone could help me, I'd be grateful. If there's something you need me to find out, I'll try to look it up as it is requested. (as long as it has relevance) If I cannot fix it, I will have to reinstall the PC, but that's stressful both to them and to me, so I'd be hoping to avoid it at all costs. (See, they really like their computer the way it is, and I would have trouble returning it to its exact state, so I would like to avoid that.) Thanks in advance for any help, I'll be looking forward to hearing from you experts on this forum.