Look for the real simple things first.
Have a look at the battery and check the possitive and negative terminals are nice and tight. Then check and make sure you have a good earth connection. Whilst your at it if your bike is not fitted with a MF battery check the electolite level is between the upper and lower markers.
If you are happy with that try changing the main fuse even if the one in possition now looks ok because it's often really hard to see any faults on a fuse.
Good luck
Grizzly
