USART Stops Receiving Characters

[breesy]

Hi,

Im having a problem where the usart sucessfully receives characters for a few seconds, each time sending a response, however inevitably stops receiving characters after a while (Interrupt is not triggered, and RCIF doesn't get set). I have set DEFINE HSER_CLROERR 1. The PIC is connected to the computer via a wireless serial link using an XBee, should the 3.3v serial ouput from this module be cause for concern? If I connect the Tx and Rx lines together I get everything i send echo'd back. There is <5mA ripple on the serial and power supply lines. Any ideas?

Edit: Might also be worth noting that the PIC continues to run, for instance it can still HSEROUT while not receiving any serial input.

Edit2: It appears not to stop receiving characters if the oscilloscope probe is connected, does that sound right? It is listed as a 10MOhm, 33pF probe.

Regards,
Daniel