MS-Essentials-claims-I-haven't-scanned-in-a-while fail

According to MS Security Essentials, my PC is at risk because I "haven't scanned in a while" (i.e. five hours ago). How often does this thing think I should scan? It's a bug, right?

When and how often does this notice appear? Immediately after startup or when you're in the middle of doing something? Does the notice disappear after a bit and things change to a green (protected) status or do you have to re-scan your machine? If the notice appears immediately upon startup it's possible you're just experiencing a bit of lag time before MSE fully loads. Especially if it disappears on its own.

If you recently scanned your machine but then install a system image (for example) the MSE will tell you you're unprotected, need to update, need to rescan, etc.

If you go to the settings tab you can turn off auto scans. Mine did that for a while and i turned it off and it has stopped doing it. hope that works for you!