Compressor 3.0.5 Question

This happened to me twice. First time a few months ago and the second time was this morning. Compressor would go
to 99% and stay at that point for a long time. When I cancelled out of it I was able to create a DVD menu, a TS file and
successfully burned and played the DVDs.

Any opinions as to why Compressor would do this?

Thanks,

Tom