I have found using the Sony MSAC-FD2M Floppy Disk Adapter with my FD-95, the contacts where the memory stick plugs into the MSAC-FD2M start loosing good contact and when this occurs, the 'C:13:01 error' message appears. The contacts sometime get so loose that a piece of Scotch-tape must be used to keep the memory-stick from falling out of the disk adapter.
This may explain why the "smacking method" sometimes works.
I don't see a simple method for opening up the MSAC-FD2M Floppy Disk Adapter case so the contact's tension could be manually adjusted.
Charles in Mason Texas