I'm sorry if I'm too vague about what exactly is going on during the lock up, but i'll attempt to describe my problem to the best that I can remeber. How it started: Upgraded RAM from 512mb to 1024mb (two sticks of 512mb), both are identical. After upgrading to 1024mb POST would freeze. I downloaded 32 updates for XP Home Edition Service Pack 2 (if the KB####### such is needed, I can get that) hoping they would fix the problems in the OS enivroments (the lock ups). This only seemed to aid the problem in being a pain. Attempted to do a system restore before the updates where installed, but it locked up about 1/2 through. The POST freeze was fixed by downloading updated bios. The lock ups continue. Its happened 2 times while browsing 5+ pages in Firefox at the same time using the tabs, I've had it happen at least 3 times while playing Day Of Defeat, I could play it for 5-20 minutes before the entire system locked up. 1 while downloading a few files through Bitlord, and had another more recent one while right clicking on the onboard sound for my motherboard in PC Wizard 2006. This, however, produced a BSOD with the Machine_checksum_error, i'm not 100% of the exact information but this is the only BSOD I get so far and is reproduceable. Some of the lockups I've had may have had the BSOD screens but they were somehow not displayed. I've also had 2 seperate minidump logs, though when reading through the "Before you post minidumps" that I should have 5 to 6. But since I'm having trouble reproducing the problem from time to time (except the BSOD with PC Wizard 2006), i'll attach them anyways to see if they can help at all. EDIT: Experienced another lockup while attempting to un-window UT2004 as well as another 3 minutes into a game. Also disabled my onboard sound via bios, tried to start up and got a lockup at the Windows XP welcome screen. Turned off the PC and tried again, locked up BEFORE the welcome screen, set onboard audio to Auto-detect in bios and comp booted up fine. Total seen BSODs: 2, both from PC Wizard Thats about as descriptive as I can get. Technical specs: OS: Windows XP Home Edition SP2 Motherboard: Abit NF8-V, nVidia nForce3 250 chipset CPU: AMD Athlon 64 2800+ @ 1800mhz RAM: Kingston Hyper X PC3200 512mb x 2 Video card: ATI Radeon 9800 Pro using 5.11 cats Sound card: Soundblaster Live PSU: Generic 350 watt Hard drive 1: 14gb IBM (has OS installed on it) Hard drive 2: 80gb Maxtor DVD-Rom: Memorex 52max 325216AJv2 CD-Rom: TDK CDRW121032 DirectX: 9.0c I'm unkown as to obtaining the driver versions for a few of these items, but if the driver versions are needed then i'm sure I can find them.