Hi magicblueman and welcome to TSF !
Are you using some particular application when that stream write error appears ? Are you playing or encoding video files ? In this case the problem could be with that application and you may need to uninstall/reinstall it.
Go to start => run and type eventvwr.msc. Search the different sections there for errors or warnings corresponding to the times of the crashes and tell us about the source and the event ID. Double-click the error and use the third button on the top right to copy the information to the clipboard then paste it here.
If the errors seem to be related to only one application then the solution could be to reinstall that app. If it's related to some windows system file then you can run the system file checker or make a repair install. If there are memory errors or disk errors then it can be some hardware failure. Tell us about it and we'll tell you what you need to do.
If the crashes are related to several different programs then it may be caused by some hardware problem : overheating, faulty memory stick, power failure or errors on the hard drive. Solutions are to clean all the dust that's in the case, test your memory for errors, check that your power supply is sufficient for your rig and test your hard drives for errors with the manufacturer's tool.
Could you post your system specs ? See the link in my sig. If this is a desktop don't forget to include the brand, model and wattage of your power supply which you'll find on a sticker on the side of the power supply box when you open a computer case.
Do you have an XP install CD with service pack 2 included ?