When I start my car in the morning, I let it warm up for about 10 minutes. When I shift into drive, my car will NOT go forward. Actually it drifts backwards a little. I generally have to put it back into park and let it run for an additional 5 minutes and then when I put it into drive, it goes forward. I did have it checked recently and the mechanic said there were some fluids leaking and he didn't know where they were coming from. He recommended that I get a DI-test. Does this sound like a transmission problem? Is there a recommendation based on my description of what is happening?