Heater/Wiper controls

[nikp]

I\'m hoping that someone will be able to help here. I have a wierd problem:

A couple of times recently I have noticed that sometimes when I hit a bump, the wipers and heater controls just stop. Nothing on them works. This happened last night (Forutnately, I didn\'t actually need them to be working) up to, and including when I got home. So I was sat on the drive, waiting for it to cool down, and once it had, I turned it off. I thought I\'d check the controls at this point, so turned the ignition back on, and the controls worked.

Does anyone have any idea what\'s going on, as this could be dangerous if it\'s raining and they stop (Happened once before christmas, and i had to pull over and stop - then they worked again). I thought it might be some sort of connection to one of the fuses, but I tried wiggling all the fuse boxes with the blower on, and it never stopped. Heeeeeelllllppppppppp!!