Hi my dad has a Asus x5DIJ but when he turns it on it goes straight to a blue screen and say an error has occured and then restarts. I've tried F8 and selected repair your computer but this took me to a black screen with a white bar along the bottom which said please wait loading I left this over night but nothing happened!
Try F8 again, but this time select Safe Mode. If it can start, you get the system with reduced functionality, e.g. it uses a generic video driver, that's why the screen resolution is low, but it still gives several options, like trying to find out what caused the blue screen from error dumps, or reinstalling drivers, or running a virus/malware scan.
If these things don't help, then you can consider backing up your important files to another hard drive or DVD, and then do a "restore to factory setup". That is if the recovery partition has the restore image, or you have it on DVD. Consult with your user guide for the step-by-step guide.
If that's not available, then you can do a clean install from a Windows install disk.