Hya Wiloughby. That could be lots of things im afraid.
Updating windows would be a place to start indeed.
Also go to start / run and in the run window type in:
sfc /scannow >enter
Have you XP CD in youre drive, and it'll run itself, replacing any missign or damaged protected XP files.
install and run
RegSupremePro.
It will want to make a backup of your registry , let it. Once it has finished, click on the Registry Cleaner tab, select Aggressive. When it has completed, click on Select, choose All. Click on Fix, and let it fix everything that it finds.
And run a test on youre
ram with Memtest:
http://www.memtest.org/
Please download
ATF-Cleaner.
Run ATF-Cleaner:
First check "Select All" , and then remove the tick infront of "History".
Then click Empty Selected.
When you get the "Done Cleaning" message, click OK.
Let's see if any of this helps first.