Has your 10.1.5 ever downgraded itself to 10.1.3? Mine has.

[redplague]

About two weeks ago, my system started feeling really sluggish and buggy and I got about two kernel panics a day, which made me so angry that I started shouting at people for no reason and driving like a psychopath.

Then one day, I accidentally click on "About This Mac..." and what do I see? "Version 10.1.3"!!! Effing incredible I found that, seeing as I've been running 10.1.5 for weeks on end...

So I reinstalled that 10.1.5 combo update, which this time took only like 10 minutes, and everything was fine again.

I still drive like a psycho and shout at people for no reason, but at least my Mac is happy again...