I think there is a good chance that the Access MDB is corrupt. A simple MS Access Compact & Repair might do the trick.
That error code indicates a type mismatch between what is being sent to the database and the actual field type. Line 901 in version 7.92 is:
.Fields("Location") = strLocation
The Author.Location field in the Access is Text(60) and in the SQL version is nvarchar(60). Both allow null's and aren't indexed, so basically, the field should allow absolutely any character or no text at all.
What version of the WWF are you running and is it Access or SQL? Does the data for a new user actually get stored? If so, can they change the data after they've registered?