What needs to be repaired/replaced on a 2002 Outback when the door switches (driver and passenger side, front and back) to open and close the windows have stopped working completely

When I purchased this car new, the windows switches would open and close intermittently but since the problem never presented itself when I took the car to the dealer, I was told there was no problem and no repairs were ever done.  Lately the windows would only open when I started the car after the engine was off for a while and would work only for a few minutes.  A few days ago I turned the window down one morning to clear the moisture from the glass and it has not worked since.  I purchased a new door switch motor and replaced the other one but it did not help.  Can you tell what might be wrong?  A mechanic said he checked the relay but that didn't help either.