I have a strange problem with an older XP SP3 PC, Intel Dual-Core 1.86 MHz 1 Gb RAM Nvidia GE 7600 GS (just a basic office and simple games config, hope I got all the specs right from memory).
A month ago the system crashed for no apparent reason, taking with it all restore points. I got outside help who managed to repair the system without reformat and reinstall, and who installed SP3 at the same time. Lots of other things were changed so it's difficult now to see where the problem comes from. Whatever application you're using regularly (about every 10 min or so, I didn't time it exactly) freezes for just a few seconds. E.g. as I'm typing this suddenly the keyboard won't respond for about 10 characters, then it continues (annoying when you're typing blind). The same with Word, Excel etc. If you have a game on full screen, it will minimize itself. There is no crash or anything, I have the impression there's a software conflict somewhere making XP time out for some hidden function and then resume. It's not dramatic but it's annoying and intriguing.
You may deduce from this I am not a computer technician.
My help guy removed Avast Pro and installed AVG 9 Free, but that slowed everything down. I uninstalled AVG and reinstalled Avast, the pc works faster but the problem remains.
I updated the Nvidia driver, no result.
I ran CCleaner, SpyWare Cleaner 4.05, and TuneUp Utilities. Apart from removing somewhat too many entries (but I recovered those), no difference.
System maintenance shows no hardware conflicts.
Hard disk was defragmented some time ago, no discernable problem there.
Before the SP3 install this problem has never occurred, but as I said a lot more than the update happened.