I have reloaded my script after using section access. And after publishing when I am trying to open it is showing the error like Unsupported file format.
Looks like ur file got corrupted. I would say better u take back up of the application when ur trying to use section access in the script and reload it.
The other option would be go and check the log file for the the qvw, may be you can find why its getting corrupted.