Over,
The problem may not be the main breaker but something loose in the panel causing an excess load. Turn off the main breaker and tighten all connections including the ground and neutral bus. Stay on the load side (breaker side) of the main as the line side (street or meter side) is still very hot. Before you turn the main back on, load shed (turn off) all circuit breakers and then turn on the main. Now reset each breaker one at a time until all breakers are back one. Turning the main back on under load is never a good idea. Any questions or concerns, PM me and I'll walk you through. If you have a good amp meter, there's even more you can check beyond that.
Thanks Wkmac, I will do that my next day off!
DO NOT PULL THE METER! Many local codes prohibit this by anyone other than a licensed electrician and doing so could open up a whole can of worms you might not want.
And I won't do that...
It usually happens when the dryer is running...But the breaker for the dryer doesn't trip. I figure if it was a dryer or dryer circuit problem, the dryer circuit would trip.