The only thing that comes to mind is that perhaps there were drivers installed on the dell that ran the keyboard. This might screw up the HP keyboard that you're trying to use. If there are drivers installed for the dell keyboard, uninstall them then plug in the HP keyboard (and install drivers if needed). You should be able to uninstall any drivers for them from the "Add & Remove programs" option in the control panel.....it's just a matter of finding the correct ones to remove
If either is a specialty keyboard (media keyboard etc.) than they'll require drivers for all the extra functions to work. I should think that dell drivers wouldn't work well with an HP keyboard
Alternately, keyboards are fairly inexpensive. You might want to consider going to your local PC shop, or a Walmart (or where ever, even order one online) and picking up a new one and using it.
Hope this helps! If not, let us know and we'll go from there!
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