random BLACK SCREEN trouble!

[beneath_the_surface]

COMPUTER INFO:
I have a HP Pavilion dv5 lap top with Windows Vista.

PROBLEM:
I've been having this problem for about a week. The computer is running but the screen randomly turns black for 5-15 minutes and then when it goes away the computer is still operating in the same task it was before the screen went black. Also when starting the computer it fails to start and I have to perform a start up repair. Sometimes I have to turn the computer on and off four or five times before the start up repair will show up, and then it will let me fix the start up problem. I really need my computer so getting this fixed as soon as possible is a MUST!

WHAT I'VE TRIED SO FAR:
I've updated my drivers using a program called "hardware helper", which is specifically for Windows operating systems. I went to the ATI website and downloaded the correct driver for my computer and this didn't help. I've also tried to clean the registry using a program called "registry mechanic".


I don't really have the money to bring my computer in the get it fixed so I'm hoping I can get some good advice about what might be causing the problem. I'm also not super technical with computers so if you could reply in the simplest terms possible I would appreciate it.

[Allan]

1) Using utilities like Hardware Helper or Registry Cleaners will CAUSE problems, not cure them.
2) What is new or different since the last time everything worked properly (ie, new hw, new sw, virus, error, etc)?