2007 Chevrolet Tahoe

Drive Train Axles Bearings problem
2007 Chevy Tahoe V8 Four Wheel Drive 57000 miles

got in this a.M. Put vehicle in reverse and warning message " service 4 wheel drive system" came on and felt like I had the brakes on. Tried to reset the drive mode (had it on auto) but would not reset. Tiny lights were on on the dial for 4 wheel drive and auto. Could not get out of my driveway in reverse. Is this a sensor problem or something else. Have only used 4 wheel drive once and never went over 30 mph. Had no problem driving home last night but had this happen this morning.
January 12, 2010.

There are codes that are stored in the computer. Those need to be accessed first to know what it wants.

IF no codes are present, you need a computer flash.
Go here and enter your vin and check for calibration updates:

Have seen a fair share of encoder motors and the switch on the dash on these go bad, but would not jump to these conclusions.