[jambo]

Ok, Have you got a Haynes manual? There are several electrical tests you can run on various parts of the loom, but I would remove the rear plastics and look carefully to see that no part of the wiring has rubbed through to earth.

This not being the case, as you have the bike running does it sound perfectly normal and then just die?
Can you check that both plugs are still sparking at this point (Use a spare plug and the HT lead to the rear plug to check for spark with the tank up and nothing else needing disassembly, then test the front one in the same way). If neither one sparks it points to different components (CDI, Loom etc) where as if only 1 sparks I'd possibly suspect a coil breaking down in the heat. Let us know how you do!