Sounds like it might be hardware with the locking up and lines issues.
Try to see if it will work in safe mode (Hit F8 Repeatedly on start-up, choose "Safe Mode")
If you get the same issues in safe mode, its looking more toward hardware.
Try running some diagnostic tools like [post="http://www.memtest86.com/"]Memtest
[/post] to check the memory.
Also, if your seeing lines, it might be a video card issue, but a video card will not LOCK up your computer necessarily.
Try these steps and report back!