Car Troubles

I own a 2009 Ford Escape XLT 4wd. Over this winter we
have had a few warmer days here and there. Nothing
extreme but the temperature hit around 60 or 65. On those
days my car would start to shake after about 15 minutes of
driving. Then after coming to complete stops, the car would
struggle to move, and it would make a grinding sound.
Almost like the handbrake was still on. The car also had
trouble making it up hills. One of these days I was almost
home and started to park when the car basically almost
completely seized up. After taking the car to my mechanic,
he found nothing that could be causing that problem. The
car seems just fine when the temperature outside is cold.
But as soon as it heats up the issue comes back. Any
explanation? I should also add that white smoke came out
from the hood on one occasion.