I have an eMachines T2042, that the PSU (Bestec) croaked and fried the motherboard, so I replaced it with a ASRock P4VM800.
Now when I hooked up the PC all went well, but it never recognized the DVD-ROM and CD-ROM, but for some reason unplugging it and plugging it back in to the motherboard fixed that.
Now Windows XP run kinda fine on the PC except viewing YouTube videos would crash and I figured it was Flash 10 as it happened to other peoples PCs when upgrading to Flash 10, but even going back to Flash 9 never helped.
Rarely it would crash other times. So I tried upgrading all drivers and everything as debugging the crash claimed it was most likely a driver conflicting with Windows but upgrading every known driver still failed.
So I figured maybe one of the RAM sticks is bad (even though MemTest86+ said passed), in slot 1 was a PC2100 Hyundai Electronics HYMD132 645A8-H and Slot 2 was a Samsung M3 68L32223DTL-CB0 PC2100. Both are 256MB.
So I took both out and just put in the Samsung and amazingly no crashes, but then I tried the other one and still no crashes.
Is it possible that one of the RAM sticks was loose and that caused random crashes or could it really make a difference now that the Samsung and Hyundai are reversed in their slots, Samsung in #1 and Hyundai in #2?
Loose RAM would certainly cause crashes, as would dirty contacts. It may well be that you have cured a very minor problem by reseating the RAM.
In years gone by, when RAM came in the form of about 32 seperate chips, part of our regular maintenance was to push all of the chips firmly down into their sockets with our thumbs. They had a tendency to "walk" out of them due to constant heating/cooling cycles. Sure made for a sore thumb. At least now RAM has clips to hold it in place.