Sounds like...grinding?

Hi everyone,

I've got a 2000 Sunfire Sedan and I recently got the fan belt replaced.

When I'm a flat surface, with my foot on the brake, the car makes a grinding noise if the gear is in reverse, drive or neutral. When I'm on a slope, I hear the same noise when the car is in reverse.

The mechanic told me "there's something wrong with your brakes". Funny, I said, you just fixed the brakes for me recently.

Now he says there's nothing wrong with the car.

Anyone have a similar problem with their car? Is it the fan belt, the brakes or the mechanic???