Look in the SQL error log. iirc, errors that occur in a login trigger's execution are logged to the error log. Check what's there.
What's the schema of that table?
What database is it in?
Does everyone have insert permissions on it?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability