Hey guys. I have an old HP desktop I recently began using again after having it dormant for a couple years or so. It's an HP Pavilion a530e running Windows XP, with an AMD Athlon video card, and it's hard for me to give more details than that unfortunately because I got the computer so long ago and haven't used it for a while, and I no longer have the documentation.

Back when I stopped using it, it had a strange issue where the CD drive would always open right away when I powered it on, and if I tried to close it, it would usually just open again. I could get it to stay shut if I shut it enough times. I did some research on this issue trying to solve it and it was suggested there was a virus, but I scanned the computer very thoroughly (was using McAfee at the time and used some free programs too) and found it totally clean, so I concluded it must have been an issue with the disc drive itself. That's one reason I stopped using the computer but for what I want to use it for now I don't need the disc drive, so I just figured I'd ignore it. I am not sure if this matters for the current problem but I thought I should mention it in the interest of thoroughness.

Anyway, I started using the computer again 3 days ago with a new keyboard and monitor but with no changes to the hardware, and it has been working flawlessly up until now. This morning I went to power it on and it seems to turn on, but the monitor isn't getting a signal (it does say "no signal" if I turn the monitor off and then on again). I also checked to make sure the monitor hadn't gone bad with my Netbook, which it received signal from just fine. I can hear the fan going, but I do not see the HDD light flashing. Normally the power button itself also glows when the machine is on, but it is not glowing except for very briefly when I first press it.

My knowledge of hardware has a lot of holes in it (it's just made of all the things I've learned by osmosis) but it sounds to me like a motherboard issue perhaps? I am inclined to think it's pretty bad that I don't see an HDD light flashing. Is it possible it's the hard drive? Is there any chance replacing RAM could do anything? Just wanted to get some opinions of people with more expertise with myself. Thanks for reading!

EDIT: Not sure if it matters (probably not) but I forgot to mention that the CD drive opening issue does still exist under these conditions, which is one way I know at least SOMETHING is turning on. It still even stays shut after a few tries. Very weird issue. It also seems to supply power to the USB hub I have plugged into it.