Blizzard Downloader keeps blue screening my PC.

I am having a serious issue that I have had for a while and I don't know what to do. For some reason, the Blizzard Downloader, will get to a certain point in the download process and then, my computer will go to a blue screen saying, "Windows has encountered an issue and has to shut down" or something along that line. I had this issue a while back, when I tried to install the StarCraft II beta. I ignored it and just waited for the game to come out. StarCraft doesn't have this issue at all and my experience with it is great, no crashes. World of Warcraft, didn't have this issue for a while, then when the cataclysm patch come out like a couple of weeks ago or so. The process will get half way through downloading and do the same old blue screen error encounter thing. I can't even play the game I am paying a monthly fee to play. No other game on my PC or anything else has this issue. Just the blizzard downloader on WOW. I tried a few things, dumping registry files and cleaning the computer up. It did nothing. Eventually today, I decided to just reinstall Windows 7 and loose everything and I did that. I re-installed starcraft on disk, no issues when patching. I reinstalled wow on disk, and when it came time to patch, the whole thing happened again with the blizzard downloader downloading the patch. This computer is now clean as hell, as I just dumped the partissions and re-installed the OS. WHAT THE HELL IS GOING ON?
Please help.

My specs are: Intel 2.8 GHZ Dual Core Processor
4 gigs of DDR 2 ram
GeForce 9600GT
Windows 7

If any of that info can help. Please for the love of God, someone help if they can. I would greatly appreciate it.