A bad switch is not likely to cause shorting like that as most times there is not a ground wire at the switch, the individual circuits have a their own gorund and the switch just breaks (or connects) the hot leg. But it could be vaugely related to the switch, as another circuit could be shorted to ground or shorted to the circuit that is blowing. At this point you need a schematic (wiring diagram) and a volt/ohm meter. If you don't have one, the cheapest place to buy them is Harbor Freight. This one will work for THIS issue just as good as my $500 Fluke meters, so no reason to go all out and get a nice one.
http://www.harborfreight.com/7-funct...ter-98025.html
Try to get a digital version of the wiring diagram then PM me for my email and send it to me and I can try to give you pointers to look for. As it is now you need to get that meter asap and I can tell you a couple things to check prior to getting wiring diagram...but I gotta run off to work now...I'll check back in when I get home