I think, I screwed up the color profiles on my macbook as you can see in the example shot, the color in the image are not consistent on my macbook. In the finder the image looks nice, but in Quick Look and iPhoto there is too much red in the images. The effect happens with photos I downloaded from the net, like this one, and with pictures I have taken with my camera. 

Do you have an explanation?

Thanks for your time in advance!

[added info] 

I experienced this problem on my 2008 macbook with photos I shot myself as with images I downloaded like the example image. Furthermore did I put my macbook to sleep and attached it via dvi to a dell P2411H trying what mspasov suggested. So I am not sure if my playing around with the color calibration ( I ended up using the existing Color LCD profile) actually fixed or that it was only a coincidence that the images looked normal again.

One idea I had was that maybe OSX/iPhoto/Quicklook sometimes get 'confused' on how to treat color profiles in images when another monitor is attached. I know, that sounds very far fetched. What do you think?
This is probably caused by bad color calibration profile. You could load the default profile for your hardware, or try to calibrate your monitor.

Try loading the default profile of your display. This is done by opening Preferences -> Displays, Choose the Color tab and select the Color LCD (I'm asuming MacBook PRO, on other machine or external monitor this will be different).

If this doesn't help - try calibrating your monitor by pressing the Calibrate.. button and following the onscreen instructions..