Why do i get one long beep?

[TANGFIRMER]

I worked on a computer recently. I removed the hard drive to have it scanned and replaced it. When i restarted the computer it got a loud beep that would not stop unless i unplugged the machine and the machine would not boot.

The machine has a phoenix bios so i checked the list of beep codes to see what the beep means but there is no reference for the beep i was getting. What could cause this beep. Can anyone tell me?

The computer is a desktop pc running windows xp that is only used for surfing the internet. He complained of it being slow and the cpu is always busy so i tried to help. IT has no anti virus, no firewall and no ad ware and spy ware remover. I decided to  remove the drive put it in an enclosure and scan it with my anti virus. When i scanned the hard drive i found over 500 viruses mostly Trojan horses.

The motherboard is an integrated board with only a pci 56k modem installed.

At the moment i cant tell you any specifics about hardrive, memory or service packs because the pc is at my friends house. I would have to get that information and put it  here tomorrow or so.

[Dusty]

Can anyone tell me?

Not until you tell us what breed of pc you worked on.  Please read this..

e.g. the following was posted in response to a similar query referring to an HP laptop.  We can't be expected to give you a diagnosis of any kind without knowing what we're trying to deal with.

The continous beep usually means a memory failure (RAM) or video memory if a plugin card is used. Check to be sure the unit sees all of the memory, a weak power source( without AC adapter) could cause a partial failure of one memory card. Another fault would be that the battery is very low on charge and won't accept any charge. BAD Battery. You really need to check out the user manual for the real meanings.