My 03 had the same symptoms about 6 months ago. Driving along fat, dumb and happy the thing would just die. Sometimes ot would restart itself, sometimes I had to pull to the side. As it was due for the second valve check (about 55k miles) I put it in the shop and explained the problem. He checked all the kill devices and could find nothing wrong. Did find about a dozen corroded connectors within the blocks. he replaced those, cleaned and lubed all, said give a shot. Happened agian the very next day, 7 or 8 times in succesion. After reviewing in my mind the scenarios of restarting, the fact that the dash never went dead, all together pointed at a kill mechanism. I reasoned that it was not the clutch switch, as pulling the clutch in did not allow it to start. Sometimes only pulling to the side and finding neutral would work. The next day my brother and I made up a jumper wire, and bypassed the kickstand switch totally. Unplugged it just under the tank and put the jumper wire in to complete the circuit.
That was about 3 thousand miles ago, I guess one of these days I will clean the switch and try that out. But for now, I just make sure the kickstand is up just like I did before the idoiot switch came into being and all is well.