False positive error message in MS Access (concurrent users)

I have discovered a strange apparent bug in MS Access and would like to know if others know it already and hopefully how to get around it. Trying to count records based on known column categories. One particular set of records can't be saved or output because of apparently one or more records in that range. They appear to have some corrupt character which is generating a false error message: "Another user is currently using this record" or words to that effect. Is there some obscure character (combination) that can cause Access to lock a record? It is physically impossible that anyone else actually has access to the DB. There could conceivably be all kinds of strange characters in there because the data come from a wide variety of sources. I think I have narrowed it down to a personal name field but this is not a final verdict...