I've had my 748 die on me a few times, absolutely random, where lights and stuff work, but starter (and fuel pump) doesn't work. I wait a few minutes while on the side of the road (what else am I to do?) and then have been able to get everything going again.
The sidestand relay (a little relay next to the fan relay, same size, and flasher in that rubber "grouping" next to the battery) was the culprit! Looks like it might have been damaged by a bit of battery acid or some such. The plastic housing had a small hole in it.
Amazing little relay... when it goes bad (even if you have the sidestand switch "by-passed") the bike will not run or start.
Not the most stupendous news ever, but handy to know when the problem arises. And it was pretty damned frustrating to me! Glad I found the little bastard! Only $10-$15 from Ducati (I didn't bother to look for an alternative, but I'm certain they exist. It's just a relay )
Maybe this will help if someone else goes a searchin'