nadya, you have unlock the record or the file each time you save data even there is no users is in the same records the record gerts locked and you do not release it then you again try lock it so it gives you this message, I have faced the same problem while I was using fp2.6 on novel.
be sure each time release the file or the record after saving.
best regards
Best Regards,
Hisham Serry
IT Management