CSS Tableless Style Sheet HELP [ASAP]

Hi all,

I've been beating my head against the wall trying to sort out an issue I have with my current style sheet, and making it backwards compatible with Internet Explorer 5.1 on the Macintosh.  This for both Mac OS 9 and OSX.

What occurs is the style sheet "collapes" [for the lack of a better term].  Everything imploads, and get's jumbled to the lefthand side of the browser space.  What is weird, is the fact this does not happen all the time, only sporatically.

a) All other browsers work fine. [ie: Safari, FireFox, Mozilla, etc]
b) Heavy use of php includes.
c) makes use of a header, righthand nav, subfooter and footer include, both assigned properly in the style sheet.

Due to the nature and content of our website, we are forced to support Internet Explorer, so this is a must.  Please don't ask 'why' we support IE, or what your general impression of IE is - what I need is to get it fixed and move forward, rather than telling me how much IE sucks - we all know that already. 

--- I would like to pay someone to fix this for me.  Any reasonable person with the skill level in CSS should probably know right off what is causing this.

--- If you're genuinely interested in making a few bucks and will hang in there and fix this problem, please contact me through this forum.

--- I will be happy to provide more details off-forum rather than listing more here.  We can either chat, or correspond through email.

Thanks in Advance!