WinXP / H-P Pavilion a316n

This is driving me crazy. I need help.

My wife brought home a computer from a friend of hers at work. His brother shipped this to him and he wanted WinXP installed on it. Why she brought this pos home I have no idea.

Opening the case showed 2 optical drives, but only one power supply plugged in. HD was wedged in the cage. Not even screwed in. Geez. I kept trying to boot from the CD, and it would go so far then blue screen. Checking the BIOS, I found that the HD was not being recognized. After farting around with that for 15 minutes, I found a bad HD cable, replaced that, then it worked.

I used a Win XP Pro disk. WinXP found 3 partitions. I deleted all of them, then created one partition. Ran format. And then XP installed. After installation...

Bootloader kept popping up and giving me the choice of XP Pro or XP Home. Supposedly Home was deleted. Theres only one partition now. I fixed that, and now it boots o.k.

Now I got another stupid problem. While I was working with all of this and installing Pro...no problem. With Pro installed, I'm having problems turning on the computer. I press the on button and it powers up, beeps once, then turns off. It appears to do this when its warm. When its cold, it turns on. If its warm, I have to press the power button 5-6 times before it catches and stays on. My first thought was memory. But I had a lot of extra memory laying around. Tried different memory. Nothing worked. Not all of these could be bad. Now I'm thinking the power switch might be bad. But what could the one beep signify?

Thanks for the help. But the less I have to deal with this, the happier I'll be. XP is installed and it runs o.k. when its cold. I'll tell the guy he might have a problem when it gets hot. I tinker around with computers on my own, but I really don't want the responsibility of screwing something up for someone else and then getting blamed for it.