Basically I'm having issues with my system freezing when gaming or surfing the web. They're slightly different in what happens during freezing so not sure if they're related. When I'm on the web in forums, surfing or whatever the system will freeze but I can still move the cursor with the mouse and the blue circle icon is still moving showing it's still thinking. I give it some time to see if it's just hung up but it just hangs there so when I hit ctrl+alt+del the system totally locks up and I have no choice but to hard reset. When I'm gaming the screen goes black but the game is still running and the sound is still fine but nothing will get me out of it except a hard reset. I've also had the screen flicker and only the top 1/4 of the game is visible at the top of my monitor and the bottom 3/4 is black. This has made me think it might be video but I've tried running them 1 at a time to see if one might be bad but they seem to work fine. I've also thought I might have a memory issue so I'm in the process of running 2 sticks at a time instead of all 4 to single out bad sets of RAM. I completed this build in April 2011 and it seemed to be running fine up until June. I was away on business for a month and returned the first week of July. Of course there were updates and I didn't heed the warning if it's not broke don't fix it so I updated my BIOS to 1409, video drivers to 275 etc. It seems that everything started after the updates but I can't recall for sure which I apologize. I was getting USB power limits exceeded popups from win7 and popups stating win7 has detected your system as being slow would you like to set the desktop to Basic blah blah. I tried several things to figure out why I was having some of these problems along with the freezes but nothing. I got frustrated and decided to just start over so I wiped the drives and reinstalled windows. Still have the freezes but I don't get the USB and slow system popups. I've made many changes one at a time in BIOS enabling, disabling, auto etc to see if there is something the system might like but nothing helps. I'm at a loss at the moment and hoping someone who reads this might have similar problems or someone might have a solution. Any help is appreciated. Thanks

Here is my system specs:
Maximus IV Extreme BIOS 1409
i7 2600k CPU
Corsair Vengeance CMZ8GX3M2A 1600C8 16gig 4x4Gb(currently 2x4Gig)
Corsair AX1200 PSU
EVGA 580 GTX x2 in SLI slots 1 and 3
HT OMEGA Claro 7.1 sound
WD VeliciRaptor 150 x2 Raid 1, WD VelociRaptor 300 x2 Raid 0
Water Cooled