Hello. I'm new here, found the forum via googling. I've been having slowdown and BSOD issues on the last few days. The first time it happened was on a previous Windows installation. It was running very sluggish at times, or more accurately, it'd suddenly lag, and sometimes that'd lead to a BSOD. I do not have the minidump from that installation; I'm not really a computer person so I didn't even know minidumps existed before I did some research. I also formatted my HDD since the computer was working very poorly at the time - this seemed to have fixed it at first but then the booting issues and the BSOD came back the next day. The lag has been around for a while. It's working as fast as it should but then it'll suddenly get sluggish and laggy when I try to open my browser, or play a video on youtube or MPC, or sometimes during a game (not graphics intensive); and then it goes back to normal. In other words, I get lag spikes. They never culminated in BSODs before last Tuesday, though. Speedfan temperatures look fine during these lag spikes. I ran memtest and fixed my paging file as the sticky advised. I also cleaned the computer inside. Booting is still slow, and computer still lags at times. Here are my computer specs: CPU: Intel Core 2 Duo E6550 @2.33GHz 2GB DDR2 RAM Mobo: Asrock Conroe1333 D667 GPU: GForce GT240 512MB PSU: Power Cooler Maximum Power Supply (450W, the box says maximum output is 530W) I already updated all my drivers except for the BIOS. Here are the error messages I got on boot, which is why I fear the worst: * NTLDR is missing. * Disk read error. Press Crtl+Alt+Del to restart. * Reboot and select proper boot device or insert boot media in selected boot device and press a key. * Primary Master Hard Disk Error. Press F1 to resume. The HDD is a 500GB western digital that's less than a year old, because my 160GB HDD stopped working last october - this is why I'm wondering if the problem could be the disk or the mobo. I'll add any other information you need, but I might need a hand on how to acquire said information. Minidump file is attached. Apologies for the long post, and thanks in advance for the help.