It could be that the foot pedals function as another key, when not being used within the Sony Package.
For example, you can configure the 3rd button of a mouse to be a particular key or function, perhaps the same can be done with this footpedal.
Therefore, if the person is using the footpedal and goes into word and hits Shift and another letter, if the footpedal is setup to act as the Ctrl key for example, then they PC could recognise the command as Ctrl+Shift and the letter, which could be a shortcut command for another function.
I am not familiar with footpedals, so not sure if the device would appear in control panel or if you would need to go into the specific software for the pedal (Sony I would guess, if the pedal came with the application) and see if there are any settings relating to the Pedals serving other functions, or as other keys, and if possible disable them.
"Stupid isn't not knowing the answer, it's not asking the question