Alright, so when I'm going in Advanced view in the Antivirus - Shield window, under "Real-time protection is enabled", there is that "Last system scan" part. Well, I noticed yesterday morning and again this morning that it says "Last system scan: never", despite the fact that I did already two Deep System Scans since then, yesterday and today.
BD 2009 doesn't give out any errors saying that it didn't scan so I imagine it's a display bug or something?
Maybe this has something to do with the fact that yesterday morning I installed the IE8 Windows update? Because I haven't seen this happen before.