Computer boots up but then the screen freezes

try reset CMOS.or re-wiring the electrical wires,make sure they are seated tight.

Try not using your bluetooth

Try a System Restore and select a restore date before your problems started.
To get to the System Restore - Click on Start - All Programs - Accessories - System Tools - System Restore

sounds like you have a virus boot your pc in safe mode to do this press f8 on your keyboard after the first startup screen you should get a screen up with boot options choose safe mode let your computer start up then run your antivirus program when finished reboot computer hopefully this will solve your problem

It could be with your RAM

This might happen if you install McAfee with applications running, or not restarting Windows, etc. I am not sure why you couldn't boot in Safemode, booting in safemode is exactly what you need to do to uninstall McAfee.

Some files can be missing, try to start your computer in SAFE-mode, if it works you can try again, othervise you have to repair you XP-version. Add me [email protected] for more instructions.

Make sure that your hard drive is set as first boot device and disconnect all the USB devices from the system and than try to boot.

check that all cables are securley fitted to your drives . try unistalling the graphics card , boot up the computer , if it boots up then you will need to install the drivers that came with the graphics card first

Corrupted driver or faulty hardware perhaps.