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.