I recall plinking around with server-side traces a while back and vaguely remember that if Profiler is writing to the file, it locks the file. I had to write a job to stop/start, forcing a new file and releasing the old one for importing into my table. My requirements needed the trace to start before prime time and end after primetime rather than 7/24 so I had 3 jobs: 1 to start in the morning, 1 to stop/start throughout the day at intervals and 1 to stop for the night.