I agree with Paul. Capture to a file. Ditch hyperterminal if possible too. I'm guessing you are using cut and paste using hyperterminal.

This seems to happen quite often on boot log captures for some reason - probably the 115200 baud with no flow control doesn't help eventhough the average PC should be able to hand those kind of data rates.

Edit:
Oh and we use a large number of these USB-serial adapters quite successfully.

Looking at the log, it seems it's overwriting things. You can see player messages at the very beginning of log well before the player even starts.