First of all, the information given by you is not sufficient to fully describe your problem.

My impression is that your speed is unnecessarily high. Do you really need the 38400 baud speed? If not, drop it to 9600 and see if that helps improve things for you. Another thing you may try is to 'pace' the output from the PIC using the define meant for that.
Code:
define  CHAR_PACING  1000
' define the character pacing in microseconds