We've implemented a review system for building permits using workflow. Part of this includes reviewing plans in adobe acrobat as the advanced versions allow us to use the measurement tool and etc. A couple of participants have been experiencing the attached errors (see photos).

It appears that it may have to do with the document being left open for a long period of time and it timing out or experieiencing refresh issues. For example, the most recent time that it happened, our reviewer left the document open and went to lunch. When he came he attempted to save and close the document and experienced the following errors. Nobody else tried to open the document while he had it open.

I'm wondering if anyone can further clarify what is causing this error. Also, if there is anything that can be done to avoid it (in addition to not leaving documents open and leaving their desk which we've been advising them).

Thanks,

-Jeff