When you upgraded to 5.05, yoiur Singers.mdb database file was first backed up in the same folder as your Singers.mdb. OR... you now have your "prior Singers.mdb" also on the new computer in the same folder. Now, only one file can have the name "Singers.mdb", so copying your "prior" file overwrote your Singers.mdb that was converter when you ran 5.05.
You will now need to run 5.05 again, and it will report it is making a backup (overwriting the prior backup) and then a message that it is being converted.
DO NOT interrupt it for any reason. It will destroy your Singers.mdb file, and possibly the backup file when you try to run 5.05 again. 