I've been running into about the same issue lately. When I boot my computer, everything's fine for a couple of hours but suddenly I begin to receive all sorts of weird messages.
It usually begins with my network drives not being available anymore (and Windows saying I don't have enough resources to access them). When I try to run task manager I get the same error as Francisco (0xc000012d). I also get the messages about quota, invalid dlls (not ole32 though) and the "not enough system resources". Sometimes, I manage to close an app or two and I can get access to the task manager but it shows that roughly 60% of my RAM is still available and the CPU is idle. It seems like if Windows is suddenly not able to access the memory or disk properly, and system runs out of resources.
The funny part is that all those problems were happening on my previous computer and I thought the old hardware or a clogged Windows installation was the culprit. But since, I installed a fresh copy of Windows on brand new hardware and the problem shows up again!
On the new machine I did all the updates (SP3 and every other fixes) and I'm thinking since this problem appeared recently, could a recent update from Microsoft cause all the trouble? Other than that, I installed pretty much the same softwares that were on my previous computer. Programs that I use on a daily basis include Avira, Outlook 2003, Chrome, Dreamweaver CS4 and Winamp (doing web development while listening to some music
The whole behaviour and the delay before everything crashes are quite inconsistent. I've searched a bit on google and I found several people having the same issue (some back in 2008 and others more recently) but no solution have been found so far. Everybody is posting hijackthis and anti-malware logs but it doesn't seem like a virus problem...
If someone has a clue on that one, please share your ideas!
Thanks for any help!