I have not followed the recent MOSFET/motor switching threads
too closely, but do recall talk about PICs being reset by motor
switching, etc. I ran across the following design note while
surfing for info on noise in ADCs:

"Resistors Protect Microcontrollers From Capacitively Coupled Spikes".

http://www.elecdesign.com/magazine/1999/dec1799/ifd/1217ifd4.shtml

16F84 was being used to control gates of MOSFETs [IRL530] which
provided two-phase variable-frequency drive to a motor. Switching
spikes were being fed back thru the parasitic capacitances of the
MOSFETs to the PIC and resetting it.

10K resistors inserted between the PIC and MOSFET gates fixed
the problem. Note - they don't show a lot of other protection
[catching diodes/etc] here, but use of the series Rs looks like
a good design idea in such ckts.