Toyota Repair: Transmission slips when engine is cold, engine cold, engine rev

Question
1999 RAV 4 2WD 43,000 miles, manual transmission. When the engine is cold, the transmission slips when letting the clutch out. It will not slip if I rev the engine up and let the clutch out. Once it's driven for a while this problem stops.
No service work done with this problem.. no repair history.
   Thanks  

Answer
Sorry, but I'm a little bit confused, if the clutch slips when taking off normally it should slip even more when the engine is revved up more, I need more information as to what exactly happens, so try to answer thes questions for me so I can make sense of this:
With the engine cold and you put it in gear and make a normal takeoff, does the car move?
Does the car stall?
Does the engine rev up but the car won't move? Or does it move slowly with increasing engine speed?