Log SQL Server (Current - 20/12/2009 00:00:00)
Message 'ImportSystem' is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc column in sys.databases"
Simple one this, the error tells you exactly what to do...
select log_reuse_wait_desc, * from sys.databases
The log file cannot be reused due to an Active Transaction.