Get yourself a solistek 600/400w dimmable and be done with the issues.....have you tried powering it up directly thru the outlet, no timer attached? Also have another bulb to check? Just suggestions that you may or may not have tried.
Succesful growing will be determined with the quality of equipment you have. It can happen to any brand though you always have to be prepared. Companies do not make equipment that lasts a lifetime anymore.
The money is not in the cure, but it is in the medicine, if you get what im saying.