Here's the latest:

I checked for the missing items within the questionnaire today by running through several conditions within the experiment. The last half of the items within the questionnaire are still being skipped, however this error is not happening in the same conditions that it was when I posted previously. So, again, the error seems to be occuring randomly. When I select the questionnaire and run it on its own (as opposed to running it within the larger experiment), I don't see the problem occur (although the file loses its formatting that way, i.e. no quickstyles).

We are currently running MediaLab version 2006.2.39 on all lab machines using Windows XP.

Thanks for whatever ideas you can summon.