I use HP Wireless Keyboard (model 5187-4441), working via USB-plugged receiver. The keyboard has some useful special keys (for example: mute & volume control), which, at the moment, do not work.

Some of the keys, those that can't be reconfigured, work, but they do not display any messages on the screen when they're being used, as they used to do. The reconfigurable ones do not work at all. Otherwise the keyboard works fine.

This is probably a software related problem, as in the keyboard settings of the control panel there's no keys displayed on the key configuration interleaf. The list of configurable keys is empty, but it used to be full.

If I try to switch some of the advanced setting of the keyboard (for example: there's an option to state that Internet connection is available, for the network related special keys to work), rundll displays the following message (originally in Finnish, sorry for the poor translation):
"Exception when trying to execute program shell32.exe, Control_RunDLL 'C:\WINDOWS\SYSTEM32\main.cpl",Keyboard".

This happens even if I terminate all the excess processes running at the moment.

I've tried to reinstall the original keyboard drivers, but it was of no use. I've also tried to locate updated drivers, but it seems that HP does not offer any updates for this model.

My operating system is Windows XP Home.

I doubt that my other-than-keyboard-hardware has anything to do with this, so I won't post the specs for now. I don't know if this could be caused by some software that I've installed. On the other hand, I haven't installed much of anything during the period when the problems started.