Hi guys, hopefully someone can help me with this as it is starting to drive me crazy I have built a new system and components are as follows: Core i3 2120 Asus P8H67-m-pro B3 revision OCZ3G1333LV4GK ram (2 x 2gb sticks DDR3 dual channel) Samsung 1TB HDD CoolerMaster case with 420W PSU Windows 7 Premium 64bit + ATI Radeon 4650 Graphics Card (from an existing system) This is the only part of the system that is not brand new. The system was first built without the 4650 card installed as I intended to use the i3 2120's graphics for basic day to day functionality. During the first installation of Windows the installation froze at the checking video performance screen. I restarted and the installation continued without incidence. Later that night i received a number of blue screens all with different error headers. As i couldn't find a fix for these errors I formatted and re-installed the OS, this time with the 4650 installed. This time the installation was trouble free. The system ran for close to 12 hours with no errors until another BSoD. I have installed all available Windows 7 updates as well as all current drivers available for devices listed in device manager. There are no 3rd party games, antivirus/firewall or software installed as yet except for CPUID and other diagnostic programs used to try and solve this issue. I have run both the windows memory diagnostic tool and Memtest+86 v4 for 12hr+ sessions with not one error recorded. I have run the sfc /scannow utility as proposed in a number of threads and it crashed during the first 3 attempts before it finally completed the scan. BSoD continued however. There doesn't seem to be any consistency in terms of when the system crashes. So far it has happened during downloading of windows updates, running of sfc /scannow, general web browsing, it crashed twice while using the SF Diagnostic tool requested for this thread. If i leave the computer sitting by itself during the day just at the desktop it will eventually crash. Also, on a couple of occasions it has locked up while in the Asus Bios page when clicking on the advanced settings tab. This was after I had entered Bios straight after a crash. I thought at one stage that it might have been the ram voltage as manufacturer website lists it at 1.65volts and bios had it shown as 1.5volts. I have sinced tried 1.5, 1.65 and auto with seemingly no difference. BTW, the 4650 card is from a system that has run the last 12 months or so with no problems whatsoever. That OS was WinXP though. Also, as i have been trying to type this thread i have received numerous reports about windows explorer and internet explorer having stopped working and crashing. I'm not sure if any of this helps but if there is anything else you guys require let me know and I will get it to you a.s.a.p. Thanks in advance.