You have to determine whether the PC or the Keyboard is at fault. Having said that I'm not sure which type of PC you have and which operating system. On some IBM compatible computers it is possible to turn the comm ports off via the computer setup. If you are running Win 98 I would right click on the my Computer Icon - go to properties and then to ports - see if Comm1 & comm2 are active with no Yellow ? marks.

Not sure if that helps but its a good place to start.

Jerry