I have been experiencing very frustrating errors from Windows XP for the last few months, and cannot pin down what's causing the problem. A few times a day, seemingly at random intervals, most of the following symptoms occur (sometimes accompanied by the "ding-dong" error chime):
1) Clicking on the Start menu brings up only the top group of items (Set Program Access, Windows Catalog, Windows Update) in a small popup. Everything else (Programs, etc.) is gone.
2) Alt-Tab no longer gives a display of open windows; it just cycles thru the windows.
3) Clicking on taskbar groups does not bring up the list of individual windows in the group.
4) Erratic window display - e.g., sometimes it will just be a blank grey box, sometimes the menu options will be missing (replaced by a white bar with just a windows logo).
5) Ctrl-Alt-Del does not bring up Task Manager.
6) Various functions do not work (right-clicking, opening certain folders)
7) Some programs crash upon opening, or do not work properly.
To resolve the problem, I close one or two applications, and then usually everything goes back to normal within a few minutes (or at least I'm able to open Task Manager, which enables me to kill and restart explorer.exe).
I'm hoping someone here can help me identify the source of this problem. Thanks!