I have the same symptoms as you; started about 2 months ago. Very random and only done it 4-5 times. I also have wipers that will come on then off randomly on their own, and when they are on intermittent, sometimes they wipers stop working and I have to turn them to hi then back to intermittent for them to work properly again.
With that being said, the common denominator is the MFS, and I am confident that it is the problem. I bought a new one last week and will be installing it when the rain stops, hopefully in the next few weeks. I believe the issue with the MFS is the contacts get corroded and/or deteriorate.
Here is some info that I am using on:
http://chrisb.users.superford.org/Gr.../Projects/MFS/
http://www.clubgp.com/cgi-asp/mods.asp?modid=141
http://www.clubgp.com/cgi-asp/mods.asp?modid=178
