home screen wont stay dim

i have my home screen set to dim after 20 seconds idle. but it will not stay dimmed. as soon as it dims it just lights right back up. and its not recieveing call email text messages or anything. I can just have it sitting on a desk and watch it dim down then light back up until i just decide to turn it off. this is really killing my battery life. has anyone else experienced the same problem?

have you tried pulling the battery to reset the device?

yes... tried that it didnt work

Reinstall the OS? If you already tried that too, I would have to say its defective somehow, like possibly the light sensor has gone bad or something. Haven't heard of this one before.