The pc starts and loads.Then the blue windows xp screen comes up and it wont do anything else exept let me move my mouse pointer around the screen

Restart your computer and then press and hold F8 keys until you get Advanced Options menu screen.Use the arrow key to highlight Safe Mode, and then press Enter, your computer will boot automatically to safe mode.
If you able to start in the safe mode then you need to update all your drivers and install all windows updates from Windows update and scan your computer for viruses!And I also suggest you to run CMD as administrator and write in CMD without quotes"sfc/scannow"
this will fix blue screen error.
If problem still exists, then get the reliable program like PC Fresher to fix your annoying blue screen problem.