Different Color Results Using DisplayPort & DVI on Same 2011 MBP

Hi, I have a strange issue going on...

I just purchased a Dell U2410 and have my 2011 MacBook Pro connected to it via Mini DisplayPort to DispayPort. I noticed some of the colors were dull, but left it as-is.

Today, quite randomly, I hooked up my late 2007 white MacBook to the monitor via Mini-DVI to DVI and it reproduced the same great color I was (frankly) expecting from previously using an iMac.

Curious, I then disabled the DisplayPort cable from the 2011 MBP, and hooked up MDP-to-DVI and voila! I was able to get the same color results as the older Macbook over DVI.

So I'm left scratching my head: What is causing the MDP-to-DP connection to give differing color results from the MDP-to-DVI connection? Any ideas?

Thanks

 

I figured out the issue, but still looking for a solution: The MBP thinks the monitor is a TV and displays in YPbPr instead of RGB. The latter keeps getting ejected when I try to switch to it.