I had the same problem and there is a sensor in the top right side of the screen itself--if you have a cover, take it off, clean the area on the screen that corresponds to the hole in your cover, and you should have fixed the problem. Just a dirty/greasy screen. : )

 

On my X the hard key lights wont turn on at all most of the time. I have no case on it. I have to power it off to gt them to turn on. Anyone else having this issue?

 

I started to have this issue as well after the gingerbread update. It is very inconsistent as to when the lights turn on.

Looking at the light sensor value (using Elixir) I did notice it had a high value in a dark room. After I turned a light on/off if did drop to a lower value and the backlight came on.

I don't know if this is the sensor logic or Elixir not updating, will have to try with another app.

It is very frustrating since I end up pushing on the edges of the buttons half the time which does not trigger them.