brightness issues

[+ OPTIMUS +]

hi there.

I'm using the breathtaking configuration of an iMac pro 24' with Windows7 running on it.
Issue is:
today we calibrated the monitor, which's default overbrightness and yellowness caused suprises when sending stuff for another comps or printing.
Starting tremulous resets its changes, or, at least it generally boosts up the color. This was always an issue but it wasnt that much of a pain as it reseted after alt+tabbing, or quitting. Only after crashes it was a real problem because i had to reset the computer to bring it back to normal again.
But now, something (prolly the settings of the calibration) resets the brightess in every one minute. So it doesn't matter if i'm ingame or in the menu, or i set the brightness up again, it goes back to default-dark in a minute or less.

cheers and looking forward for help.

Edit1: the probles seems to only appear in window mode.
Edit2: depending on the fluctuation of the computer's emotions.

[David]

But macs just work!
Obviously you're lying to try to make macs look bad.

* David knows nothing about macs, so will shut up now.

[Demolution]

This (for me) usually happens when I connect some kind of hardware via USB or that hardware undergoes some kind of drastic change mid-game. But then again, I don't have a Mac, so I'm not entirely sure why I'm posting here...