run time error 9 when press keys by accident

[labwork]

In the beginning of the experiment, participants read welcome screen and they are asked to click continue to move on to the next screen. There is a slight chance that some participants may press keyboard by mistake. If they do, a message appears saying "run time error 9, subscript out of range" and the MediaLab collapses.

Is there any way that MediaLab doesn’t respond to pressing keys even though participants are supposed to click continue?

Or is there a better way to deal with?

Thank you.