...try the steps I listed. If the printer is an older model, then try visiting the HP site and looking for updated installation software. Uninstall the printer per their instructions and then reinstall it using the updated software.
Also, it's important to be using Service Pack 3 on Windows XP as the earlier versions had a few issues with various stuff. If you're not using SP3, please do so.
It might also be a good idea to run Chkdsk. Try running Chkdsk in "repair" mode to find any damaged files and correct them. Start by opening a command prompt as an admin. RIGHT click on the Start button, choose "Command Prompt (Admin). (Or type "Command" in the search line, then RIGHT click on the "Command Prompt" listing at the top, choose "Run as admin".) Once there, type chkdsk /f /r /x, leaving the appropriate spaces between the letters as shown, then press the Enter key. You should see a note that it can't be run till a restart is done, type "Y" for yes, then press the Enter key again. Close the command prompt and restart the computer. Chkdsk will run upon restart and will take quite a while to finish.. Don't panic when the progress bar stays at 10% for a long time. It's fairly normal and the Chkdsk process may take a couple of hours.
When it's finished, it will boot to your normal startup/lock screen and you can login normally and then see if things are working correctly again.
Hope this helps.
Grif