ps/2 port of the case doesn't work properly

Hi guys,

I'm going to install Win XP on my computer (I had win 7 but had some problem with installing the HP printer on it and so I decide to install XP because that printer seems to be installed properly on XP).
Now When I put the XP CD on the CD driver, it says press a ker to boot from CD and I press the Enter key, (now the keyboard works) after that, within installation time when that I should press Enter to install XP, this time the keyboard doesn't work.
My guess is that the ps/2 port of the case has problem (it's old and somewhat has been broad).
Now what is the solution in your point of view please?

My system manufacturer is "ECS" and the system model is "945pl-A".

PS: When I what to enter to BIOS, (on the top of second black and white screen it has been written that "Press shift-F10 to configure) and when I press these two I enter to an environment that seems to be the BIOS but it has very few options! I'm not sure is it BIOS, or how to go into BIOS in that motherboard.

One of my problems is that "I'm not sure that place is or is not the BIOS" but that place hasn't many options, especially for keyboard and mouse.

I read all answers and tried all keys when that (installation screen of XP) appears. But no key works!
I found what key is needed to enter to BIOS. In the first black & white screen it has been written that to go to setup press Del key.
But there is a huge strange thing here. When I press Del key it does not work (and does no go to the BIOS for manipulating) but after this first screen (and in the second black & white screen) when I press Shift-F10 to configure, the keyboard works here!! And also when I press Enter (when the press any key to boot from CD prompts) the keyboard works here as well and goes to installation page!!
But only on first screen it doesn't work and therefore doesn't go into BIOS setup!!

After these, I inputted one keyboard by USB port. It worked and I could to go into BIOS. Then I changed the settings which I'd think it's better to change it. Then I inputted the XP CD and could to go through the process of installation. Until now it's in progress and no major problem has been occurred.

About the ps/2 port of the mobo, I think it has some problem related to hardware or...