I apologise for this being long... I have been trying to fix my PC now for 2 and a half months and i've torn my hair out over this and i really hope someone can help me. I recently upgraded my motherboard to this: 6000 Athlon 64 X2 Dual Core Board Bundle + 1GB DDR2 Memory, ECS GeForce6100PM-M2 is the motherboard name and a 400W PSU, CD drive, no graphics card at the moment as it has onboard graphics and right now i just want the PC to turn on, but I'm intending on using geforce 8800gtx at some point (i know i will need to upgrade the psu i guess) and i have tried 3 hard drives, none work. One is the original with Vista Business edition on, when I turn the PC on I get a screen saying 'Please insert repair disk etc etc' so I have and it does nothing and the same problem happens, a blue screen flashes, monitor turns off and i go around in circles, I tried to downgrade to an oem version of XP and the message I now get is a black screen with the simple 'Operating system failed' and that is IT. I called out a PC guy and even he didn't know what to do.. -.- ! So i gave up on that hard drive and have tried to use my old hard drive which has windows XP home edition on now i get this error: STOP 0x0000007E (0xc0000005, 0xF68AE750, 0xF78C242C, 0xF78C2128) I have looked on the forums for solutions but things like deleting or removing the drivers is not really something im 100% sure on how to do and i don't want to cause any more problems.... I also tried a repair with the xp disk but the problem just repeats again... I do have a disk which came with the motherboard which contains all the drivers according to the manual but of course, it wont let me run this is safe mode and im not even sure if that is the issue. Any help would be SO SO appreciated, i'm falling behind on my uni work because of this, and am rapidly losing my sanity! thank you -edit: i would like to add that i have a 3rd hard drive that has XP on also, but it gets stuck at the authentication screen, i have the product key for it, but when i type it in, it does not generate an installation ID??? I know I can activate it online, but it just wont pick up the connection....I have the cable plugged in the LAN and it flashes, but it still says i have no connectivity...is there a way I can fix this?