I’m not exactly sure under what conditions a BOM may cause errors, but I had the problem a while back on Windows and it made me crazy as well. The PHP parser seems to have problems with it. Just make sure you have the correct setting in your Editor. For example I use PHPDesigner and there is a checkbox like “Include BOM”. Also I’ve used Adobe Dreamweaver before and from time to time a BOM just got dropped into one of my php files. Then I had to use hex-editors to delete it…
I don’t know of any other troubles. It’s just the problem with the php parser I think.
Was the BOM already in the main.php which you may have downloaded from here?