After a lot of searching, I've decided to post in hope that someone can help me...
 
I have recently inherited a Latitude D610 at work.  I've used one before and liked using the Fn + Up and Fn + Down buttons to adjust the brightness.  This D610 doesn't change brightness -- even when running off the battery it's fully bright.  Here's what I've done so far:
  • Verified that the Fn, Up and Down keys are working
  • Updated the BIOS to A06 (the most recent)
  • Installed / Re-installed the Intel Graphics Video driver
  • Installed / Re-installed the Dell Quickset application
  • Sacrificed a goat
  • Scoured any and all Settings and Properties screens for options

I hope that someone can help.

Thanks,
Romaniello