I haven’t noticed a pattern yet as to when it happens, but my (Win7, up-to-date, with MSE) laptop will occasionally claim (for a few seconds) that I have no spyware protection. By the time the notification fades away (in the below sshot, you can see that it’s already fading), the icon goes back from red to green and everything’s apparently hunky dory again.
I’m guessing there’s either some race condition in the spyware protection (hopefully not, although it’s a small window) or MSE is taking too long to an API call or whatever, but it’s a bit disconcerting as a user experience to have my OS say “THIS IS BROKEN! FIX IT!” immediately followed by the green check of “nope, sorry, just kidding, we’re cool” and have that happen repeatedly.
Thankfully it only happens on a basis of something around once a day (probably not that, but within an order of magnitude) so I haven’t (yet) gotten too worried about whether there’s a real protection problem or not 
I’ve done an offline scan of the drive (popping it into the BlacX connected to my Windows Home Server) since this has started just to make sure it’s really fine and not already-pwned, so hopefully it’s just a cosmetic bug and not a symptom of a deeper problem
