I've spoken to the developer about this and confirmed that there are two likely reasons for the error:
1. SQL Server is still writing to the file
2. SQL Monitor is still reading the file (we only read from the trace files when an alert comes along that can be associated with trace data - like deadlocks or long-running query alerts)
It's possible to check this using a tool like Process Monitor: ( http://technet.microsoft.com/en-us/sysi ... s/bb896645
) but I'm doubtful that it would help diagnose the problem.
A couple of questions:
1. Are there any clockskew issues between the base monitoring machine and the SQL Server being monitored?
2. Are there any performance issues on the SQL Server being monitored or the base monitoring machine?