After disc clean up runs and shows the summary you should have this
This is a list of steps you can run through
You can check for an improvement after running sfc /scannow then after each step until you have run through them all, if necessaryClick start then run, type prefetch then press enter, click edit then select all, all the files in the folder will now be highlighted, right click any file, click delete, a box will appear asking if you want to delete all the files, confirm the delete then rebootOpen the CD ROM Drive used to install Windows, insert the XP CD but leave the drawer open. Click start then run, type sfc /scannow then press enter, then close the CD ROM Drive drawer, You will get a blue progress bar, after the bar goes, reboot. This will check for and replace missing or corrupt system files.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 shouldIf no changePlease go here to repair your operating systemRepair XPIf you are unable to run Repair XPAlternate XP Repair GuideUse the last one - Windows Installation CD to repair the current installation, which uses a slightly different methodWindows XP repair feature won't delete your data, installed programs, personal information, or settings. It just repairs the operating systemAfter running the repair it will be necessary to install all Windows UpdatesI left both repair methods in, so you can see if you get different results
Clearing Prefetch is to make sure XP does not try to load files from the previous install, (pre-repair), it should not but just in case
sfc /scannow will replace missing or corrupt system files, which you should not have any of, though it is a quick check
chkdsk /f /r will check and repair the drive, if at all possible, if it cannot then at least you know the drive is a contributor
System restore, open it then click system restore settings, then you can either:
reduce the amount of allocated disk space, this will mean XP will offload older restore points to make way for new ones, sooner than at its default 12%
If the PC is running well, you can turn system restore off, click apply, reboot then set a restore point to give just one, though the important thing is to do this when you are comfortable with the way the PC is running