2001 Buick Regal moans

Does anyone have a clue what would make my 2001 Buick Regal moan? It literally makes a moaning sound - particularly at low speeds when you are turning and breaking at the same time. It also seems to slip a bit when stopping.

What model is this? LS/LSE or GS/GSE and how many miles?

When was the last brake service?

It is an LS with about 123,000 miles. It had frt rotors and brake pads put on plus rear brake pads at 108,120 miles on 6/24/07. Sometimes when I'm stopping, it moans and slides for another 18 to 24" before stopping. But, I'm not always braking when the car moans. You can definitely "feel" the moan, in the steering wheel, brake pedal or floor board. Got any ideas?

I read a similar problem on a previous posting that was talking about a strut bearing. I really don't have a clue. My hubby has been a mechanic for years and he first thought it might be related to rack and pinion, now thinks it might be related to the traction. [My car has a button you can push to turn traction on/off.] He is stumped, but will follow up on suggestions posted here. [I had a problem with the catalytic converter once and you nailed it.] Got any ideas?