The weirdest thing just happened to my Windows 2000 setup now — it stopped responding to the secure attention sequence (i.e. ctrl+alt+del), killing tasks like McAfee’s avsynmgr.exe (chief suspect) became impossible (access denied) and logoff/shutdown became impossible (the dialogs would display but not actually do anything). All the while, apps continued to worked fine. Poking at the reset switch solved that one.