For anyone else where codecowboy's solution did not resolve the problem try this...
I had a very similar issue to what I think your experiencing over there... After hours and hours of trying to resolve it by coincidence I figured out that the problem was an extra space at the bottom of my custom functions.php file.
So... go and try this. Open your themes main folder and look for your functions.php file. Now go to the very bottom of the page and look for the closing ?> php tag. Now, make sure that there are NO tabs, spaces or line returns after the > including any comments or anything extra.
For me this fixed my issue and I think its a wordpress problem. If your still having the issue check to see if your calling any external php files within your functions.php file and if so do the same steps as listed above. Hope it helps someone.