Display won't stay awake -- black screen (but not BSOD)

OK...I updated my ancient 2003 HP Pavilion a330n desktop running WindowsXP SP3 on Wednesday 4/21/2010. I had 6 updates (two were DIX Dvd products, one was Picasa, one may have been Crap Cleaner, can't remember the others.) Then I saw an ad for C-Net update thingy and downloaded that and left my computer scanning it's software to see what CNET thought needed to be updated. I had to go to my kids' program so I was gone a few hours. When I got back, the screen was black. It won't be normal even after rebooting. It DOES show, just for a flash, a normal screen of whatever program it happened to get to while I was hitting various keys when I jiggle the mouse or hit the enter or arrow keys, and quickly goes back black before I can DO anything to it. So it is booting up and going somewhere, the display just won't SHOW me. I don't see ANYTHING, just a black screen without a cursor or any words. So I can't get task manager to show up, I can't get it to go into safe mode or CMOS or anything. I can't restore because I can't see what I am doing! I can't remember if it had a Nvidia update but I really don't think it was one of the six I updated. It seems to be sounding like the CPU is awake but the screen won't 'stay' awake. help?!?! -- Tabitha

 

so, I hooked up my laptop to the monitor to use it as an external display to see if it was a monitor problem, and it is doing the SAME THING --- so it is obviously a monitor / hardware issue. Thanks for the suggestion! I assumed after all the updates that I had screwed up some software. :-Z Now, any ideas if my Gateway LCD monitor (bought about 3 years ago) is toast or fixable? It does flicker to life once in while. The 'Power ON' light is always lit up and does not flicker.