This advice was given out on another forum and I think most people here already know about it, but if not it might be a good idea to test it out, though I myself would probably just reinstall the system I am sure there are others who would prefer to regain their working systems so for them:

Click start, all programmes, accessories, system tools to run disc clean up, click more options then clean up restore points, click confirm, click OK. Then from system tools, run disc defragmenter.

Click start then run, type prefetch then press enter, click edit then select all, right click any file then click delete, confirm delete, then reboot

When it has loaded to the desktop, click start then run, type sfc /scannow then press enter, you need the XP CD and get a blue progress bar, after the bar goes, reboot.

When it has loaded to the desktop, click start then run, type chkdsk /f /r then press enter, type Y to confirm for next boot, press enter then reboot.

This will take an hour, it will appear to load normally then either the monitor will show progress or the screen will go blank, do not disturb this.

When it gets to the desktop, the system files and the hard drive will be as they should

Get the trial of Tune Up 2006 here

Tune Up 2006 Trial

Run disc clean up then registry clean up then click optimize to run reg defrag, which needs a reboot

After the reboot, click optimize then system optimizer to optimize the computer, select computer with an internet connection from the drop down menu, this also requires a reboot

After the reboot, click optimize then system optimizer to accelerate downloads, select the speed just above your actual connection speed, this requires a reboot

After the reboot, click optimize then system optimizer to run system advisor

If no change, the next thing to do would be a repair install, this will leave all data and settings intact.

end.
Hope this helps someone, does anyone here feel it is missing something that might improve it, wording, tools, etc.,

No it's not you but I think there is a clue in the topic header.  And I would endorse TU2006 as I have just bought it, one of the few paid programmes on my box.  I have never had a good experience with sfc though 'cos it wipes out all updates.