More than likely you have a bad capacitor in your ballast pack. Magnetic halide ballasts use a capacitor, the ballast, and the bulb in series. The capacitor is limiting the amount of current that can flow through the bulb among other little roles. The fuse is probably popping because that capacitor is shorted.
In this situation, bypassing the fuse will make the lamp light and seem normal, but there is nothing other than the ballast to control the current flow through the lamp. This WILL cause your [expensive] lamp to fail prematurely, and WILL cause your ballast to overheat, possibly starting an electrical fire.
The good news is that I'm not sure just how "sticks" your "sticks" is, but almost any major electrical supply house (read: a real supply store... not Home Depot) will stock a drop in replacement ballast and capacitors (they are usually sold as a package). I'll bet if you open up your yellow pages you'll find one near enough to drive to that's less than an hour or two away. I will warn you to call ahead. Many supply houses won't sell to ordinary people ("counter sales"), so you want to get them on the phone and try to sweet talk them a bit first, and make sure you bring cash, as many of them accept only cash or terms account.
Please follow KTS's advice. I've also been reading Acrylics posts for a while and he knows equipment pretty well. Don't bypass safety devices when you are working with aquariums.
