I recently upgraded my main machine from 2G to 3G with the left over 512MB sticks that were lying around. I had to reduce the speed of the ram for the mobo to recognize and boot with 4 sticks of ram. All works in dual channel. 2G corsair + 1G patriot. Everything is fine. Gaming is good. Hours of BF2 no crashes. Recently I cleared all the temp files and wanted to run the HDD defrag but it wouldn't run. A DOS screen opens and hangs for a while then disappears. Nothing is happening. I also tried to run from command prompt still the same. Did I screw up anything? Machine specs on my signature. Help please.