Hi Teresa,
Does this thread help at all? You did mention version 8.1A, but just in case...
Adagio Payables 81B upgrade errorThere was a previous problem where some data files had incorrect network rights associated with them. The solution after the error occured was to ensure that full rights are available on all data files.
Another reason for this error is that data files are missing or that a temporary file wasn't cleared properly some time ago and now a new process cannot create a new temporary file to overwrite it. This scenario is data-dependant which is why other data sets would work fine. Try running a data integrity check and see if this finds any problems.