Googled this and found lots of different reasons why this may happen.
Drove my daughter to school the other day after a good size snowfall I was in 4wd...continued on to work and both the VDC and Slip light came on when I switched out of 4wd for the drive home.
I should mention that the 4wd doesn't switch back to 2wd unless I either reverse or turn a hard right hand turn.
I should also mention that the emergency brake is essentially non functioning, I can press it in but it really doesn't engage...it's been like that since purchase.
Anyway, when I started up the car today the VDC and Slip were off but about 2 seconds after you press the brake pedal they come back on and won't go off...
Drove into work...went to lunch...same thing...
Any idea what could have caused this? I plan to check the brake fluid when I get home but not sure why it would happen.