An option for issues...
If you have something specific, often you'll find if you search for the issue at hand, you'll have a starting point to launch from regarding information. The stickies end up getting the most respons and attention.
Regarding your specific issue I don't have a definite response. However, if you'll excuse my elementary approach.
Is something physical binding on the axle? Take a look.
Is there enough fluid in the transmission? Fill 'er up
Have you had the transmission flushed lately? Might be time.
Do you have the TSP (traction stability program) model which makes a grinding sound when engaged? My wife freaked out the first time she heard it.
Beyond that I'd suggest a trusted (key word trusted) qualified mechanic give you his $50 opinion. Its a small price to pay to know whats going on. And from there make an informed decision.
