More information needed for someone to help... click these links and provide the requested information
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
Report back with the codec details of your file, use the programs below... a screen shot works well to SHOW people what you are doing
Also, what is your EXACT brand/model of graphics adapter (ATI or nVidia or ???) and the EXACT driver version
Example... I have an nVidia GTX285 with driver 296.10
v. CS6, brand new with most recent updates
Mac OSX 10.8.2
the files I am importing are .mov
no error messages, just flashing green screens throughout all video when I import and export from premiere
I don't have any third party hardward or codecs on my computer yet
And the answer to my last question? (the one where I gave an example)
Also, did you read the links about a file type being a wrapper, which may contain many codecs?
Without more information, I don't think anyone will be able to help
One thing I always try if having problems with a .mov it to just rename it to .mpg and see if that helps.
Answering John's questions will help allot.