Hello, I recently installed a 1GB DDR 400 Ram stick to supplement the 512MB I already had, at first everything was running fine, until I received a BSOD a few days ago. Thinking that the new ram was faulty, I checked it, and found it to be loose in the ram slot, I re-secured it, and my PC ran great until yesterday. I am now receiving periodic BSOD's. I checked my bios settings and scaned my ram for errors using the windows diagnostic tool. I found two errors One under INVC, address 407a91f8 expected 00000000 actual 02000000 One under WINVC, address 407a91f8 expected 10101010 actual 12101010 I was about to bring back the 1GB stick, but decided to test my other ram modules, all of them were showing the same errors in both my ram slots. So is there any hope to my situation, these BSODs show up out of nowhare, even if I'm not doing anything memory intensive. I ran every test I could think, of. I even scanned all my HDD's reset my bios, and scanned for viruses, I could understand one ram module being defective, but all of them? Am I right to assume this might be a motherboard problem. I haven't installed any new software in ages, or updated any of my drivers. Please, if anyone can help me, reply.