Macbook Pro 13' 2011 - Problem with external Display

Hi Guys,

I just bought a brandnew Macbook Pro 13', with a i5. So now i'm trying to connect my MBP to an external Display (Acer AL2216W), but it just does not work. my MBP regonizes my display, but it just does not show any Signal. A message pops up my my external display saying: "input not supported", i changed every(!) resolution and Frequency, still no change.
So my Setup is:

- MBP 2011
- Acer AL2216W
- a Mini-Display-Port -> HDMI
- HDMI -> DVI ( to connect to the display )

Now there are a few things, that make me a little bit... suspicious.
First:
- It works perfectly on the same MBP in Windows 7
- When i close the MBP directly at the startup, i can see the bootscreen on the display, after that, the display turns black again saying: input not supported
- It works perfectly on my iMac 24' in Mac OS X and Windows 7..

What i've done so far:

- tryed nearly every resolution, frequency and ColorSync Profile.
- Repaired privileges
- Reset PRAM and NVRAM
- reinstalled MAC OS X 10.6

i haven't got any clue what i should do anymore. I know that all cables are good to go, cause it works on other machines and/or OS'. Anyone got a solution, or knows what i could try to possibly make it work?

Regards

Christian