Keyboard not recognized by Windows XP

Hello!

A computer had a really bad virus with lots of pop-ups. I performed a
completed hard drive format and clean install of Windows XP
Professional.

When the computer boots up, the keyboard comes on and the computer
goes to windows.

The computer does not have a PS/2 port, only USB ports. The USB mouse
works, the keyboard does not work. I have tried using a different
keyboard, plugging the keyboard into different USB ports, including
the port the mouse was using. Nothing.

I tried logging into safe mode, nothing.

I reset the board by pulling up the little pin and also the battery.
Nothing.

I looked in the setup screen (which I can get to because at this point
the keyboard works) and did not see any settings for legacy USB
devices. I did not notice during POST there is a keyboard error. But
when the computer starts up, it goes from the inital screen that lets
you select F2 or F12, right to the Windows splash screen and
ultimately windows.

I am at a lost. I have no idea what to do. The mouse will allow me to
click on things, but I can not type anything.

I have read lots of forums and most of them deal if the mouse and
keyboard do not work. However, in this case, the mouse does work, the
keyboard does not.

Any suggestions would be helpful.

BTW, it has SP3. I made sure I installed an antivirus and all of the
microsoft updates. I was able to do this with the keyboard and then
something happened and now Windows does not recognize the keyboard.

Do you think if I left it on, it would receive another update from
windows and that could possibly fix the problem?

Thanks!
Melody