Dim mode (from F1 button) - display annoyingly lights after 1 min.

I hope this hasn't been beaten to death here already but I just noticed this issue after the last OS software update....running 10.6.8 on a 17" Macbook Pro and I usually never turn my laptop off at night nor put it to sleep, I press F1 until it dims and it automatically goes to sleep after 15 min of not using...easy.

Now for some reason when I dim it to maximum display light off, after about a minute, sometimes more, the display lights up on the 'lowest to dim' setting for about 4-5 minutes then continues into the mode that I was used to all these years. Happens on my girlfriends computer, identical machine to mine, now since the update. I have looked through System Prefs high and low on how to curb this as well as online, can't seem to find the answer. The closest is an issue people were having with the 'Automatically adjust brightness as ambient light changes' setting which doesnt apply here as I tried thinking it might.

Anyone have an answer for me here?

 

99 views, no reply...hope someone can help!

 

bumping up....

 

I tried this on both laptops, problem persists...I too found this 'solution' here and on other forums but it didn't fix the issue. I thought it could just be my machine but doing on both, strange!