Editing php files in vim

Hi there, I am using vim as my default editor for PHP files. The syntax highlighting normally works, but quite often if I page down or SHIFT-G to get to the end of a file, I lose all the highlighting and the text is all plain white. Does anyone know of a solution to this, or have an alternative editor that will preserve my syntax highlighting? Thanks, -- A Complete Luser <acompleteluser@penguinpowered.org.uk>