Run-time error '5' (case 15531)

[heathermuir]

I just completed making a new experiment including a slew of questionnaires in it with two conditions. When I try to run the experiment, I get through a few questionnaire sections and then I get a popup from MediaLab runtime error '5': Invalid procedure call or argument. Then I click "ok" since that is the only option and then another pop up from Windows Media Player comes up that says, " The file you are attempting to play has an extention (.) that does not match the file format. Playing the file may result in unexpected behavior" and then it closes medialab completely.
I've tried deleting certain questionnaires from the beginning of the experiment to narrow down if it was a specific one creating the issue but it doesn't seem like it's a specific problem in a questionnaire. Any thoughts?