Not a pretty technique, but depending on how much time elapses before the fail and how much data you can store, you could stop and restart the analyzer periodically in hopes of catching the error.
Also probably not that useful, but you could try waiting until it fails, then start the analyzer and do another read. It's likely that the driver won't attempt anything on the bus, however.
Make sure your firmware is robust enough that the endpoint is always ready to either NAK or accept data.
If you can slow the transfers by adding delays and the problem goes away, that will tell you something.