If you cannot get the keyboard or mouse to work during remote control, try doing the following commands first on the teacher then on a problem student (if running it on the teacher doesn't resolve the issue):
Go to a command prompt as an administrator (right-click and run as administrator on Win7 or Vista machines). If you are on 64 bit Windows Vista & Windows 7 PC's change the directory to c:\windows\sysWOW64, if not proceed normally.
Run the following command:
regsvr32 /u meinput
Reboot the system for this change to take effect.
Register the driver once more using the command below:
Then reboot the system and test the behavior.
If you are trying to eliminate a locked keyboard (due to driver conflicts, viper failing to remove the driver etc.) just run the first regsvr32 command.