Runtime Error 401 Cannot show non-modal form when modal form is displayed(case 21069)

Hello,

We are running an experiment where the participants are asked to write 3 short essays about themselves. The time they have to write the essay is limited to 3 minutes. My lab technicians have been reporting some participants (not all) are receiving an error message "Cannot show non-modal form when modal form is displayed". They report this only occurs between the second and third essays (between page2.exp and instructions3.exp) in condition 1.

I have attached the experiment file.

Any advice on how to correct this issue would be appreciated.

[ATTACH]1840[/ATTACH]

Do you have any cases where two things are being timed at once? Or where something that is not timed but has a natural duration such as an audio or video clip is running while a duration parameter is being executed? Sometimes if the timing or ending of items collide in a conflicting way, this error can arise. Or at least *could* arise.