I was gone for 3 weeks, with my laptop shut down (Yes, I really didn't bring it this time). Came back last Saturday, started the system up, downloaded the latest McAfee updates (now at Security Center build 93.151, VirusScan build 13.3.127, DAT 5593.0000), and since then have had problems with McAfee randomly indicating that the system wasn't protected, then asking if I wanted to fix it. And I usually say yes. And sometimes it fixes it, sometimes it doesn't. Right now it isn't in a friendly mood.
This system is a 2GB 1.7MHz Sony VAIO A230 (WinXP SP3). No new software was installed during this period, and no registry cleaners were run, nothing changed, so probably one or more of the McAfee updates since late March has caused McAfee to go off the deep end.
Normally I would do the uninstall/reinstall dance if I had problems, but it in reading the postings it looks like this does not really solve the problem.