weird problem with the Gravely 34z

Got the mower off the trailer and cut the front yard. Shut it off to go around to the small gate and get in the backyard to open the big gate. The thing wouldn't start. I finally realized I didn't have the brake on. Started right up but as soon as I released the brake it quit. Ziptied the switch down so I coul finish the yard but whenever I engaged the blades it would stop running. I didn't have time to mess with it anymore so I cut the back yard with the Turfmaster 30. Need to figure out what the problem is tho. Obviously some part(s) of the safety system but two different circuits going off at one time seems odd. Still runs great... just won't cut.
2009 Gravely34z 991022

Most likely something wrong with the seat switch, or the related wiring circuits.

Well this is really weird. I've been sick again. Had to do at least one lawn today so I got the mower off the trailer to check it out. No problems whatsoever.
I did run into some light rain last time I used it so I'm guessing something got wet and caused the problem.