Have any trips occurred since you tightened the connections/how warm are the breakers when they pop? It could be overload, could be nuissance tripping from overheating, or it could be cable damage somewhere causing intermittant short circuits. Given that it's multiple circuits, I'd tend to think it's probably not cable damage- it might occur on 1 cable, but the chances of an intermittant fault like that on 3 seperate circuits is rather low.
leland, the bond in question would be at the generator. If he's using a 3-pole switch, the neutral should be left alone in the main panel but unbonded at the generator; often, it comes from the factory with the neutral bonded to the generator frame and has to be removed in the field if not required.
