In AHP if I click on help>about it says version 3.236. Not that it should matter, but it shows all my plugins (AHP, Smart Macros, iWatchOut, Myhouse, and OnAlert) as installed and registered. I just tested this again and it is still working. I had AHP open and opened Vivik. I then clicked on one of my modules and double clicked the name header, which then highlighted the name. From there I was able to type a new name without issue. I then tried the same thing with the Windows on-screen keyboard in XP and it worked with that also.
I am running Windows XP Professional with service pack 3 installed and Internet Explorer 8. With that said, some things I would try:
Disconnect all external devices except your keyboard and mouse. Try it then and see if it works. If it does, chances are that a piece of hardware connected to your machine is giving some grief (e.g. taking a needed IRQ). To find out which one, plug your devices in one by one trying the on-screen keyboard after each device is plugged in. If you find that after plugging in a device, the keyboard does not work, unplug that device and continue to see if any remaining devices cause problems.
Check the windows device manager to see if there are any conflicts in there.
Also, check what applications are running and shut down some things to see if it may be a piece of software causing the issue. Being a software based keyboard application, it is possible that it could be conflicting with another app.
Outside of that, I am not sure how much more I can help without seeing the actual issue. I have been a computer hardware tech for over 15 years, I see odd issues all the time. Unfortunately many of the odd ones such as this I have a hard time fixing without being right in front of the machine.
Hope that helps
Dan B.