Do you execute the scripts on a server or on your local machine. When I changed to Mac, I had sometimes a few problems with the configarion of my apache. It had some trouble where my server on the old Win didn't say anything. Then you have to debug your code. In my case it wasn't really bad. Just had a few "untidy" lines in my scripts that did some trouble with the different linebreaks on Macs.
When you have your scripts on a server and get them via the internet, then jbennet is right. Could it be that you developed under IE? That often caused trouble because IE has a very bad decoding engine and when programmer stick to that many other browser misunderstand the code.