The nice thing about Windows XP is the simplified system restore feature:
Click "All Programs" > "Accessories" > "System Tools" > "System Restore"
Select "Restore my computer to an earlier time."
At that point you'll see a calendar which has scroll arrows on either side of the month. You can roll back your system as far back as you have memory allocated for saves. The bold calendar dates inticate when a system restore point was created.
In this example here's the earliest point I could find where I had done a previous system restore. Factory default settings had already fallen out of memory. But this would suffice to get my system back to a reasonable point.
Bear in mind that after rolling back your system you will have to reinstall some software and patches that were added after the restore point. If the last version of AHII that existed prior to that point was patch 8, then you'll have to reload patch 9,10, etc.
I hope this helps.