How to manage user access right that change weekly

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The site I am going to build has roughly 1000 html, php, asp, mp3, pdf,
swf, doc. jpg, txt files etc....... I put them in 100 different
folders.  200 users will be given access to 10 folders weekly.  The
folders that each user can access is in different combination and the
combination change every week.

I have read a lot on google about user access management, web access
management, .htaccess access management but still can't find an answer.
 Could anyone give me some direction?  I build the site on Windows,
Apache, PHP MySQL.

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