Hello! I can't see if the problem is software or hardware, but I am hoping and thinking it's a driver issue which make me post it in this section. I'm new here and I found this forum after days of the endless search of a problem I have. The problem is described further down the post, first background check. I just bought a new computer. Build it together myself and to help you help here is the system: Intel Duo E8600 3.0 Ghz Gigabyte GA-EP45-DS4 Corsair XMS2-6400 TWIN2X4096-6400C5 (4gb) HIS Radeon HD 4870 Seagate Barracuda ST3750330AS 7200.11 1tb Corsair HX-series, 520W * * * * * Problem The core of the problem is that I have a hard time booting my Windows OS. The OS loading gets as far as that loading screen of Windows is done, and right before the Welcome screen or login screen, the problem hits me. Also note that the problem only started after the GPU drivers were installed I tried to install Vista Ultimate x64, but problems at boot were there as well. This time it usually came up with a Blue screen of Death referring to the process atikmdag.sys. I also tried to install both Windows XP x32 and XP x64, but this time the BSOD wasn't there. This time a black screen was the problem, and sometimes I got a memory dump in white font color (maybe that is somekind of invisible BSOD). After a day or so, I noticed that the freeze/BSOD only happened every third or so time I tried to boot the OS. Note that when not installing the drivers, booting the OS went smoothly. The drivers I got were from the CD, or inofficial hot fixes, or general drivers from AMD's site, all have the same problem. But the problem happened less frequently with the general drivers. * * * * * I have run memtest86 to check the RAM, and the test passed twice without any errors. I have checked the CPU temperature and both cores idles arround 35-40 degrees celsius (far from abnormal). I have Thermalright extreme as heatsink, and put on Arctic Silver 5 paste. System temperature idles around 45 degrees celsius. The GPU is in the right PCI-E x16 slot. Two PCI-E cables from the PSU is connected, and those two cables goes straight to the GPU (they aren't shared with an other device). I've tried to do a HDD-test with SeaTools Enterprise, but they can't find a disc ("No HBA has been detected"). * * * * * Please try to help me. I have a really hard time figuring this out.