I feel your pain. It is frustrating. But, as has been said before, it's simply a matter of getting an ISO burn that's clean enough for the player to read error-free. Sometimes it's the brand or type of disc you're using. sometimes the software, sometimes the burn speed.
The lockup you report is typical following the error message. You just have to unplug the player and start over.
The official Toshiba firmware disc will work first time, every time. But if you don't feel like waiting weeks for it to arrive, you need patience.
If burning your own ISO doesn't work, maybe it would be easier to move the player to the PC and update over the net.