Hello all, I wonder if anyone can help a relative simpleton. My computer has been chugging along fine for ages, but this last week I suffered a hard disk failure. It was 5 years old, and heavily used, so it came as no surprise. I reinstalled Windows on a partition of my second disk, and thought everything would be fine. However, I seem to now be getting PFN_LIST_CORRUPT errors. I read that these are normally associated with RAM problems. However before the hard disk failure, I had none of these errors, and the two 512mb RAM sticks were working fine. I also upgraded my graphics card to a GeForce 6600 (AGP) in May, but didn't experience any problems with this. I've read two suggestions so far. First, is that the RAM is a problem. Second, is that perhaps the PSU isn't giving enough power. I now only have one hard disk and one DVD drive installed, with on board sound card and the new GeForce 6600. I'm not entirely sure where to start to solve this. I wouldn't know how to check the PSU, and I don't have a floppy drive installed (silly I know) so haven't been able to try the memtest thing I read about. Also, when I try to boot Windows with a non-powered USB hub plugged in, the Windows start up thing freezes. This suggests to me it could be PSU related. In this case, I'm confused as to how it worked ok previously, but now doesn't, despite one less hard disk to power. What would be the sensible suggestion? Try whipping a RAM stick out and running it for a bit to test? Find an XP fix of some sort? I've noticed in device manager that some RAID device isn't properly installed, and I'm not sure what that would be for. Any advice would be greatly appreciated. Many thanks, Keir Windows XP, 2x512mb RAM, notsureaboutthemotherboard, GeForce6600.