A: My computer's pooched.
B: Hmm... Can I take a look? I may be able to fix it.
A:Do you know computers?
B: Well I'm a certified computer technician so... I can't gurantee I'll fix it, but I know what I'm doing. At least I won't wrack it.
A: It's all yours.
... B sits before the computer and does his thing.
Few hours later...
A: Wow... I took this to many people and noone was able to fix it... so what exactly was the problem?
B: Well your computer was infected with a number of spywares, trojan horses, viruses and etc., and all I did was run several spyware removal programs.
A: But others who took a stab at my computer probably did the same thing, they said they ran spyware removal programs to no avail.
B: Well you've got to turn off the system recovery feature before you run any spyware removal software because, even when the removal programs detect and kill most of harmful materials residing in the system, the operating system, in your case it would be windows XP, recovers all those harms back, using the system recovery feature.
A: Why would it do that?
B: Those malwares, it's the collective name for spyware, adware, trojan horses and whatnot, are too intelligent for windows XP. The system recovery feature is designed to react to any kind of change in the opeating system's core. When those malwares intrude the system and change its core, they do so so intelligently that they manage to slip in undetected. So as far as the operating system is concerned, no change is made to the core and the malwares have become its own skin.
When you then run the spyware removal programs to kill the malwares, the operating system thinks the programs are ripping its skin apart and the recovery feature kicks in, when actually, all they are trying to do is remove harmful stuff from the operating system.
So you've got to run the feature off before you run the removal programs, otherwise you'll blow several hours for nothing. All those people you took your computer to, they probably aren't professonals.