System Error #-2015

Greetings,
I have written a procedure that analyzes an ROI in a quicktime movie, and it works perfectly on a 98 second video, but it gives System Error #-2015 near the end of processing a 30 minute video; the debugger shows the error at the following line:
PlayMovieAction frame=Findex, extract=ChunkSize
Does anyone know what this error code means? I can provide more details if needed.
Thank you,
AA
-2015 is a QuickTime error code defined as: invalidTime.

My hunch is that some 32-bit value is overflowing because the movie is so long. I don't know if this is a QuickTime limit or an Igor limit.