the problem is probably caused by bad html & the fact that ie sorta sucks on the mac imho(netscape isn't much better).
1) look for html issues like excessively huge tables
2) try to disable scripting like javascript and active content like java.
3) use a html syntax checker to be sure the pages conform to standards.
there aren't any real "php tags" for mac, nor are they necessary. the mac browsers (IE, Netscape, ICab, etc) will handle content just like their pc counterparts, but seem to be a bit pickier about the html standards.
brandon