We have a message board at work and someone just posted the same problem yesterday. This is what one of our co-workers had to say about it:

"This happened to me in my 2001 Sentra on the driver's window. It would go down, but not up. If I let the window sit for about 10 minutes and tried again, it would go up a half inch or so and then stop. Turned out it was a bad regulator that had to be replaced. I had it done under the Manufacter's warranty, so I couldn't tell you how much it cost to fix."

Hope that helps!!