Specs: Pentium D (2x3.00GHz), Foxconn motherboard (with integrated audio and video), 160GB Sata HDD, 1GB Ram, Windows XP SP3. Problem: I installed "AV Voice changer" and "AV Webcam morpher" then uninstalled it the same day. Then, after a while I noticed everything was going so slow and when I took a look at the task manager it said "System Idle Process 90", but it also said "CPU usage 50%", so I tought it could be a virus or something, so I runned a NOD32 check but nothing came out. Along with the slowness I noticed sounds (or music) didn't played well, they sounded like in slow motion, then back to normal, then slow motion, coinicidently with the CPU usage. Having both of them related, I went to the device manager and found some strange sound device and another display one (sadly I don't remember the name of them, just they were AV related), so I disabled them, then rebooted. It continued slow, but as everything seemed unnafected, I uninstalled both (I'm sure I didn't had them before). Then, I rebooted again. When I went back after terrible long loading time, the screen flickered everytime I did a mouse press. I remember that happening to me before, but it magically dissapeared. I rebooted twice changing win.ini and system.ini items and doing spyware scans but nothing came up. I tought then it might had something to do with the power supply (since I had a problem of the computer turning off all of the sudden [not logging off, then shutting down as when it overheats (that was solved by a new fan xD)], but again magically solved). I was going to just pass something to my USB drive then going for a new power supply, but then windows didn't start. BIOS showed it's stuff, and then, it never get to the windows loading screen. After three times I decided to wait a bit, but 30 minutes did nothing. I loaded failsafe defaults from setup, and it did get to the loading screen, but just like 2 seconds after it reboot. Then again the same thing. I, then, loaded optimized defaults and it got stuck before trying to load again. Doing test back and forth, now I know how to get to one scenario or the other: No matter the other setup options, if I put the primary master on just PIO it tries to load (then reboot), if I enable UDMA, however, it gets stuck. I'm asking you guys if you have seen a problem like this. I want to know if it's the power supply, or something windowish (so I just need to reinstall windows), or some other hardware, or a combination. Please try to give out options, since I don't have an easy way to get online without my PC. Thank you very much in advance.

It sounds like your CPU is still overheating...that would explain the random shutdowns & slowness. Are you sure you mounted the new HSF correctly? Have you checked your temp readings in the BIOS?

it's difficult to know if hardware related or something to do with windows. have you tried starting it in safe mode? (tapping F8 key when switching on and selecting safe mode from menu) and then doing a System Restore to an earlier date? Sometimes PCs hang for a long time going into safe mode, when there is a list of file names in white text on black screen, but they sometimes get past that if left for long enough (like over 10 minutes), so be patient at that point.

It goes like 50-55 degrees, so it's not CPU overheating. Safe mode can't start. if I try to do it with UDMA enabled I won't get to select how to start windows. If I disable it I can choose how to start windows: "start windows normally" and "last good configuration" starts loading but after 2 seconds it reboot. "Safe mode" or any of its variations will show up the loaded files, then ask "press esc to stop loading (can't remember which).dll", if I don't hit esc, it loads it, then reboot. If I hit esc it will just reboot. I've tried like 30 times so I don't think it will get solved by itself. I'll try to install my HDD on another computer (to see if it's something else), but please keep the advice coming. Thanks to both of you, and thanks in advance.

"It goes like 50-55 degrees, so it's not CPU overheating" At idle?