How do I disable the On-screen Keyboard in Windows XP?
You should be able to disable it using the Win-U shortcut to bring up the 'Utility Manager', select the on-screen keyboard, and uncheck
As an alternative, if you wish to block it on a domain, you could use a group policy to do so.
Just open up the command prompt and try navigate to the system32 folder of your window as:
Now remove every entry at startup by opening msconfig.exe and also from Registry editor by looking and googling.