My old car (2004 g35 coupe) had terrible problems with both power windows. Sometimes they wouldn't go up at all, sometimes they would go up all the way then come down half way on their own and just lock up and refuse to move! Inifiniti said it wasn't the window motors, it was the window obstruction sensor. Basically the windows had too much friction on them, and the motor would think something is obstructing them (i.e. someone's fingers..). It may also be a problem, if you recently got your windows tinted.
So far, my 3fittyZ has had a problem with the driver's side window (the car is only 4 months old btw) and the window goes up and down just fine, but it makes a scraping sound when going up.
2000 Acura Integra GS-R (sold in 2002)
2002 Honda S2000 (sold in 2004)
2003 Acura RSX Type-S (sold in 2005)
2003 Infiniti G35 coupe (sold in 2006)
2006 Nissan 350z