Multiple serial port misbehavior

The larger buffer did not change things. I did discover something unusual. My 2nd uart, the one with problems, will spit out an 'E' shortly after I send out a command string. There is no place in the code that would write this char to the uart, and I have specifically placed a filter to catch it. Either the uart driver is adding this 'E', or the uart itself is somehow generating it. Bizarre.