Can't change the drive code?

[SheGeek]

I just put a DVD in my Mac, and it came up with the drive code box thing, telling me that "The disc region does not match the drive region. The drive region must be changed to play this disc." It says "Set New Region For Drive" and next to it has a drop-down list, but the only item in the drop-down list is Region 1 (which is where I am) and the button "Set Drive Region" is grayed out so I can't click it. I have never before this put a DVD in this computer and I never picked the original drive region. (It says I'm in Region 6.)

Anyone know how to fix this?

 

[Nermal]

Is there a padlock icon in the corner? Try clicking it if it's locked.

 

[SheGeek]

Haha...I feel stupid now. Thanks!