Piaggio engine cutting out?

I have an 04 plate Piaggio NRG MC3, I bought it in November 2008 and sinse then it has cut out on me 3 times. The first time i took it home and it started up the next day, the second time we took the carb out cleaned it and it started (but we dont think the carb was the problem), and the third time it cut out i didnt know what to do. Has anyone got any ideas to what it may be, the only idea i have been given is that there may be some dirt in the fuel tank which has caused this