You've probably done this, but instead of removing just one stick of RAM, try swapping the remaining one, and if that doesn't work, try both sticks, one at a time, in different slots on the mobo. Dunno what else you could do other than that. Maybe try reseating the CPU?
I've had issues with updates as well recently.
Yesterday morning I turned on my laptop, connected to my wireless, and found that I had no internet connection. It didn't say "limited or no connectivity" but my instant messenger, weather, or browser simply wouldn't connect. After work I tried EVERYTHING to get it to work with no success. Then I got a call from my roommate from college this year, telling me that he had no internet connection. Tried my desktop computer, and found that that had no internet either. Then my sister told me same with HER laptop. Then it occurred to me that I had been seeing a LOT of windows updates this week (like one a day at least.) Looked online and sure enough, one of the updates kills your connection if you use ZoneAlarm, and you have to turn the firewall setting down to medium to get it working. Strange.