Dell Inspiron 1750 Regular Keys Not Working

I own two Dell Inspiron 1750 machines.

The keystrokes QWEASDZXC do not work on one machine.

I have tried this with two keyboards: one brand new and one from the second dell machine.

I can take the harddisk from the machine with the keystroke problem

and use it in the second machine.

I have a problem therefore between the keyboard and the harddisk as far as the machine is concerned.

Anybody got any ideas about this problem?