Using Vista, I've been having a horribly annoying problem when I "lock" my computer manually, or have it set to go automatically when the monitor goes off. It doesn't happen consistently, I have to leave the computer locked for a while to trigger it.
Symptoms include all the icons disappearing from the start menu, and the inability to open anything. Since I can't open windows explorer, or anything else, I can't take screenshots of anything.
Doubleclicking an icon on the desktop results in nothing happening, hitting windows key + e returns a dialog box with "The parameter is incorrect."
Ctrl+alt+delete + log off, then logging back on fixes the problem.
Sorry it's so vague, but it's difficult to troubleshoot the problem when I'm unable to do open any files. If anyone needs me to try stuff, I'll lock my rig overnight, and try stuff in the morning.
I've seen this before, and while i dont have a technical explination as to why this occurs, i have fixed this behavior in the past on multiple Vista Business Edition laptops.
My bread and butter cure for this is to create a new user profile and migrate all your docs, favs, desktop stuff, etc - to the new profile and nuke the old one. It's almost like your current user profile has gone corrupt.
Unfortunately, I've tried that, and while it does seem to work at first, the problem returns agains. Because it's not immediately apparent when the problem starts ocurring, I'm guessing it's something that I do/install that causes the problem, but haven't been able to figure out what.