Rich,
A few of the obvious questions first...
Did you switch the outlet that the unit was plugged into? Is it going straight into the wall, or is it going via a circuit breaker? Did you add any new AC devices (such as a new computer, TV, etc, or even as simple as bringing your Laptop home from work and plugging it in near the unit)? In other words, has anything else in the environment of your house changed, even in a different room? Is the DS7000 a day past warranty?
Chris