finderr on error -121 would support what I said :

finderr -121


-121 ISAM error: cannot write log record.

The ISAM processor is trying to add a record to the transaction log but
has received an error from the operating system. The disk might be
full. Look for operating-system error messages that might give more
information. The transaction-log file can grow quite large. To reduce
its size, you must do two things. First, make a backup copy of the data
file (for C-ISAM) or all database files (for SQL). Second, make the
transaction-log file an empty file. If you perform these steps
routinely, you can control the size of the log file.