Okay. I have an interesting issue. CPU: Socket 478 P4 512k L2 Cache/533MHz, motherboard: MSI 845PE Neo-L PCB 5.0, x2 512MB (1G total) Kingston HyperX PC2700 DDR RAM, WD 40GB IDE HD, Chiefmax 750W PSU (crappy, I know), HIS ATI X1650Pro IceQ 512MB AGP. This is NOT a new build, obviously. Here's the story. Used this computer to fix a friends computer. At the time, it worked famously. It had XP Pro SP3 and all updates, it would share files on the network without error, and it would play my games. After I fixed my friends computer, I decided to clean the system. Cleaned all dust/grime/etc.. from system. Removed GPU cooler, disassembled, and cleaned it. Cleaned off old thermal compound from the chip and heatsink, reapplied new thermal compound (Arctic Silver 5), and reassembled (this proved to be very time consuming and annoying... they could NOT have made this any more difficult to put back together). Repeated procedure for CPU. Noticed the PSU fan was burned out. Disassembled, cleaned, checked for obvious damage, replaced fan, reassembled. I took everything out of this computer and cleaned it all. Then I replaced the Mobo back into the case, hooked everything up, and now... the most interesting of problems occurs... I can install Windows XP from CD flawlessly. It runs fine. I can install all drivers. I can run Prime95 for hours. I can run 3DMark, FurMark, whatever, for hours on end and the system is stable CPU tops at about 50C. However... no matter how many times I wipe the HDD and install a fresh copy of windows... I cannot install updates. The system freezes or restarts. Nor can I connect to other computers on the network reliably. Sometimes it works fine. Other times it freezes or restarts the system. I cannot connect TO the computer FROM another computer, or the computer freezes or restarts. IF the computer allows me to use the network resources... WHEN I try to play media from another machine, the computer freezes or restarts after a time. IF that doesn't happen AT THAT MOMENT, if I try to navigate to another part of the network while I am able to play media, the system freezes or restarts. What I have done: Removed all hardware (using On-Board LAN for inet/network) except essentials (FX card, CPU, RAM, Mobo, ... ) Did not solve. Changed all settings in BIOS and tried reinstalling under approximately 30 different BIOS settings. Did not solve. At one point when I used a different NIC (NetGear FA310TX - oldie but goodie), and it still did not solve it. I disabled the FDC (no floppy anyway) in BIOS and in Windows, which did allow me to use network resources, but not stream media from network resources. However, at one time, the On-Board LAN actually disappeared from the BIOS. I noticed it in Windows said there was no NIC, so I tried to enable it in the BIOS and was baffled. I tried reinstalling and updating while all other computers were physically off and disconnected from the network. I reset the router to factory defaults. I disconnected all hardware except essentials and tried to update. NOTHING WORKS... It's like.. something that controls the network adapter on the board itself is getting hot.. or isn't getting enough consistent voltage... I'm at my wits end... and... The problem has gotten worse as I try to fix it, it would seem. lol. The VERY FIRST clean install was VERY successful, I simply couldn't use network resources. BUT it had updated Windows flawlessly. Now. I cannot update Windows or it crashes, or the updates fail. Nor can I use Windows XP with SP3 or I cannot use network resources at all. I was wondering if maybe there is a short somewhere, or maybe the PSU (remember, it did work perfectly until I took the FX card out), or the motherboard... I did memcheck I think it was (that was interesting with no floppy drive.. LOL), no errors. I've run just about every test I could think of. I did sfc /scannow in console.. etc.. etc... I tried downloading hotfixes in their standalone form, they still won't install... This only seems to happen at these times. I have not found a way to make the computer do it any other time. I am using the machine right now, actually. It's been on for a few hours with no problems... I have not tried using the LAN yet. Also, I should mention that I have better chances of accessing network resources as soon as the computer starts up or reboots than I do after its been on a while. I can use the internet fine. I can do anything I want except update windows and connect to the network... and now.. I'm sitting here... stroking my shotgun... trying to figure out what piece(s) of hardware is the guilty culprit(s)... Any and all input is appreciated. If you have a specific order of tests that you think could help me diagnose this issue, I'm open to suggestions. I really can't afford to build a nice new machine right now so I'd like to keep this one up and running a bit longer. If at all possible.