HELP: black SCREEN??

HELP! Well, today i turned on my comp and while it was loading, the usual screens didnt show up. Instead, there was a black screen w/ barely visible diagonal lines across it. It stayed that way. I tried pressing keys, but none had any effect. There was no cursor on the screen. I tried turning the comp. on and off and restarting, but every time i got the same black screen. It doesn't change. I also tried restarting in safe mode, but it wouldn't let me. I really have no clue what to do. =(
Yesterday, it was working fine. I spent all day downloading windows updates (my computer's a little behind on those--more than a year behind to be exact) In fact, after i downloaded the XP service pack it was better than fine! For a couple of weeks now my monitor's been having color problems- flickering and changing saturation all the time. But yesterday, after i downloaded the service pack, the color was back to normal, and i was SO happy! I thought my problems were over, but unfortunately, they;re not. Now just about the only thing my PC can do is turn on and off.
Anyone have any ideas as to what might be wrong? I don't think it could be a virus because I did a full system scan not more than 4 days ago. I really dont wanna call someone to come fix it, because i'm afraid they'll tell me I have to erase my entire hard drive. I know it's a stupid reason, but I really don;t wanna lose all my documents and files.
Someone plz HELP!

It sounds like a monitor cable or an internal problem with the monitor that's preventing it from syncing.

The easiest way to find out is to hook another monitor up to it and see how it works. Or, you can just take it into a shop and let them fix it.

before you take it to a computer shop, as drfeelgood said try another monitor on the computer, if it works then problem solved. but if it does the same thing then it may be a video card problem, just a matter of putting another video card in (unless its onboard video (built onto the motherboard))
if that doesnt solve the problem then you can take it to a shop.

hope that made sense.. lol

oh almost forgot, if it is under warranty dont bother doing anything yourself, get the people you bought it from to fix it, then you wont have to pay for it..

alrite well i guess i'll go try another monitor now. Hope this works! big thanx to both u guys! we'll see if it works.

I'm assuming by you saying that you tried to get into safe-mode that you still see the computer post when it first starts? If that's the case, the issue will most likely be with your video card -- it could've gotten loose from it's AGP or PCI slot (unless it's onboard video), the cable could be loose or bad or your video card is just dieing. I don't see it as a video driver issue because if it was the video driver you'd still be able to see in 16 colors.

Tell us precisely if you see anything at all when you first turn on your pc, but like I said, if you can then it's not your monitor.

Hey Cozmo in reply to ur question... no when i turn on the computer i can't see anything. It immediately turns to the black screen.

but....I tried using another monitor and it works perfectly so i guess it was a faulty monitor problem after all. Thank you sooo much guys!!! I'm so grateful for all ur help. God bless all of u!! =)

glad to hear its all working again