Do you get it if you run the questionnaire on its own? If so, can you send me the file and I'll see if I can find the problem.

We seem to have solved the problem--or at least developed a work-around for now. It's not a problem with the file questionnaire or experiment file. A new program that was installed changed the run-time on all the computers, thus interfering with Medialab. Administrator access strangely seems to make the program go away. Thanks for your help though.