I agree with the dicky connector scenario. or there could be a problem with the 5 volt regulator transistor socket, I once had a pinbot with a resetting problem (i know pinbot is a system 11 and fish tails is wpc) I tried everything known to man but it was still resetting, so i removed the 5 volt regulator transistor, (which is the transistor in the TOP3 package picured below) and i cleaned the 2 pins on the transistor with some 1200 grit sand paper, then added a smear of WD40 to the pins (be careful not to add more than a smear as this stuff is conductive, i sprayed some on my fingers and then rubbed it onto the pins without touching the case of the transistor). the transistor i reseated had a MICA insulator so i cleaned it and applied some new silicone thermal grease. (if you have the grey (silicone) insulator there is no need to use thermal grease but if you have the clear (mica) insulator then you will need to add the silicone grease. Or if it has no insulator then just add some silicone grease ( i cant remember off the top of my head if the wpc 5 volt reg has an insulator or not)
