I am also getting these messages. I'm using Vista on a Dell Inspiron 1525.
In the last few days, when I have closed the error message, Windows suggests I run the McAfee AntiSpam update which provides a solution to the problem. The thing is, I chose not to install the anti spam stuff because of difficulties I've had with it in the past, and so can't install updates for it!
I am willing to experiment if I can find the time, but if there was an update coming soon that would solve the problem (without having SpamKiller installed) I would rather wait.
Thanks for any advice,