Source files (.phps) cutting off prematurely

Hey guys and gals... I'm not sure if this is Apache, PHP, or a browser issue.. but.. .phps files get cut off while trying to access them in a browser.. anyone ever have a problem with this? I can't exactly calculate where in any particular file its doing this, but refreshing the page causes it to stop in the same place, so its not random.. Any help would be appreciated -Jason