As I noted to Yardstick, above, a windows-specific forum is a good bet for generic problems, but there are also well-respected firms that will take your computer and fix WinXP if it is a major problem for a fee.
Try to stay away from the chain-stores for such work and look for a quality computer repair shop that will guarantee the work. Make backups immediately of your working setup so you can revert back to it if you experience another problem.
You can also go to ixquick.com (or another search page) and type in something like “repair windows xp computer” and see what comes up.
Oh, and if you are experiencing continuing problems with a particular machine, find a local computer repair shop and make friends with the techs there. For a respected and undemanding customer many techs will take a few minutes to give you a hand if it is not a serious problem, as a happy customer is a repeat customer. Find people you can trust and get to know them on a first-name basis. If you don’t try to get something for nothing and their service is indeed helpful, listen to their advice and ask lots of questions. Write things down so you don’t misremember.
Lastly, be wary of any place that continues to pressure you to purchase something every time you have a problem, and only accept long-term support contracts with name-brand OEMs that you can trust. Businesses should always look for long-term support, but personal computers are generally not subject to the same wear and tear so there should be little need for them nor should there be recurring problems.
THANK YOU,