Hello Schwam07,
Thank you for the details of the issue you are experiencing with your external display.
I found an article with steps to troubleshoot issues with displays. This article is for internal and external displays, so you can skip any steps referring to the internal display. I recommend reviewing the section titled "No video or no signal, image distortion, 'snow,' or flickering" in the article below. I recommend reviewing the full article, but the following steps specifically stands out to me for the situation you are experiencing:
Reset the system
You can reset the Mac's parameter RAM and SMC.
You can find the full article here:
Apple computers: Troubleshooting issues with video on internal or external displays
http://support.apple.com/kb/ht1573
Thank you for posting in the Apple Support Communities.
Best,
Sheila M.