Bug with new keyboard or computer

My old computer with linuxcnc and stepper motors was crashed somehow and I changed it to new old PC with PentiumD inside. I used my old hard drive with linuxcnc.
It shows me nice latency (maximum 15000 and minimum 1600). I set maximum lattency to 26000. There was 42000 latency on my old PC.
My new PC doesn't have external video card and COM-keyboard input, only USB.

I bought USB keyboard (with multimedia keys) specially for it - nothing simpler was in magazine. But it has some problems:
- when I configure axis in stepconfig wizard - it types random symbols sometimes but often.
- I can't move axis with keyboard arrows continiously, machine stopes after some short random time. I use continious movement mode in AXIS, not discreet.
-I've started to run program, but it stoppes randomly and wrote me messege:

can't do that (EMC_TASK_PLAN_RUN) in auto mode with the interpreter reading

This all sounds like a very dodgy keyboard.
Can you just change keyboards?

Yes, I can.
I have at work one, I will take that. But at work keyboard also make wonders. If I don't touch anything, when Linuxcnc is working, shows window fot clossing computer (restart, turn off, so on). And it's only when linuxcnc is working.

Yes, problem was in multimedia usb keyboard.
Multimedia keyboard generates problems in linuxcnc.
I changed it to simple USB keyboard and everything works fine.