About a month ago my hard drive froze up and I replaced it with a Western Digital Caviar Black 500 gb Sata drive. I used an external USB hard drive enclosure to remove files etc, the old hard drive still worked, just wouldn't boot the OS. Well since then I had problems with boot up. At first it was just that restart wouldn't work out of Windows XP. The motherboard would beep, display it's identity and stop. Sometimes it would stop after detecting the CPU and the memory but not continue on to even look for the Hard drive or anyother bootable device. Now it takes two, three, sometimes four tries to get it to proceed to detect the hard drives and occasionally freezes on the Welcome screen to XP. When I check the event viewer it seems to get into loops of security checks, running the same one over and over. The last time I checked the System events, it showed none prior to the current boot up. I am also getting hard drive errors. No bad sectors, just corrupted files and messed up index entries. System: Amd Athlon 64, 200 MHz 3200+ about 3 years old Winfast NF4SK8AA Motherboard 3 GB Ram, 2 x 512 Kingston, 2 x 1024 Lifetime Asus branded - Nvidia GeForce 7300 GS Windows XP Home, SP3 I am also having no problems once the computer actually boots, no BSOD's, nothing untoward. Also after it's going awhile, seems to start and stop no problem. It's feeling like an old car right now. I am wondering whether to replace the current generic 450 W(DEER Computer Company ltd. )power supply with a corsair 450 W model. Looking at the Motherboard everything looks clean and appropriate (ie.. no oozing, crystallized gunk or anything like that). I have not run memtest and will do that at some point too. Virus scans keep coming up clean. Any thoughts would be helpful.