The message implies that there is something being written to the page on clubquarters.php:line 6.
Is it possible that the connection information is wrong and triggering an error?
Try adding a die(); statement after the connection on line7.
die("here");
Then see if there is something getting written to the page before the word "here" that will be displayed.
I've seen odd issues with corrupted files causing issues like this in the past as well. Perhaps creating a new blank page and copying the data fro the connection file and then overwriting the connection file will fix it. I don't really see the problem with the file either.