Lighting, Light Fixtures, Ceiling and Exhaust Fans - Fluorescent light problem

we just moved into a new home...and our fluorescent lights give out a annoyingly loud buzzing noise when we turn the switch on. we did not have any fluorescent lights in our previous home, and I am not sure what this loud noise is. Does this mean, the tubes need to be replaced, or the ballast is going bad. Also, two of the tubes go off after about half hour or so, and then come back on about 20 minutes or so later! I am not sure what is the problem here
Please help

Sometimes it means the ballast is not secure in the housing. You can remove the cover (power off) and tighten the screw holding it in. Also, the ballast only slips in a slot on one end, and could use a round of tape as a vibration insulator before you slip it in, then tighten the screw up.

Your ballast is likely overheating. Many ballasts have an internal safety device which shuts off the power when overheating occurs. This device will reset by itself when the ballast cools. It is not uncommon for the ballast to become loud under such conditions. The cure, of course is to replace the ballast or the entire fixture. If you do replace the ballast, be sure to follow the wiring diagram of the NEW ballast.

The ballasts you have are magnetic. You could replace them with electronic ballasts, which would eliminate the inductive activity of the ballast coils.