I've been researching and googling this problem for the most part of the day, and so far everything I have found has been ruled out. SYSTEM: HP nx9420 (laptop) XP Pro OS T2500 Duo Core Centrino 1.5 GB RAM (single corsair gig stick, single factory 512) Hitachi 80gb 5400rpm H/D Radeon X1600 video chip System is 14 months old... and out of warranty *sigh* Everything about this laptop is factory besides the added gig stick of corsair RAM. PROBLEM Starting roughly a week ago, I started getting errors while playing WoW (World of Warcraft, FYI). The errors were directly related to WoW file corruption and after troubleshooting and using a tool from Blizzard to detect the problem, I found out that I needed to reinstall WoW. I dreaded the all the nightmares of doing this (fellow WoWers know what I'm talking about) I put it off.... A couple of days later, the WoW errors turned into blue screen of death errors telling me the system was shut down to prevent hardware damage. By Friday night, the I got another blue screen error and upon reboot I got your typcial error message stating a windows file was missing/corrupt and the system would not boot. I started to rebuild the system and formatted the drive from the get-go. Everything went fine until XP started copying files to my drive. It would get to about 50% and then missing files would start popping up telling me the particular file could not be copied. At this point I have the option to skip or abort. If I chose to skip the file, I would have to skip even more afterwards and then it would not load windows. The files that won't copy are typically .dll's and such. They also appear to be random. My first thought at this point is that the H/D was bad. So, today when I went back to work I swapped in a new hard drive from a similar laptop. Before doing anything, I booted my system and logged in and everything seemed to work ok. At this point I thought I definitely found the problem so continued to reformat/reinstall my own copy of XP. The plot thickens... I started the rebuild process only to find that windows tells me it can't see my hard drive. However, I could get to the drive from the recovery console. I could even browse all my files and even the Windows CD. Here's a kicker... I can even get Ubuntu installed on the system without any hassle (which is how I'm online now). I even tried going back and installing XP pro after installing Ubuntu, but no luck. Other things I've tried - Reseating/removing my Gig stick (didn't get to the factory one behind the keyboard yet though) - Turning OFF the DMA/data speed option in the BIOS - chckdsk /p /r commands on BOTH hard drives (original & replacement) - Deleted/re-created all partitions on the H/D (both original & replacement) - Different Windows XP CD's - Along with several other things I know I'm probably forgetting in my frustration... Anyone have any idea what this could possibly be? I don't think it's the P/S but I could be wrong... the only other thing I could think of is the Mobo but I don't understand why I don't have any problems in Ubuntu... Thanks in advance, and sorry for the lengthy post but I know how important it is to have all the info you can when trying to diagnose a problem.