In my Wordpress MU install, every time I click on
Tools->Export or
Tolls->Import
I get redirected to the Edit Posts page.
This happens in both 2.8.4a and 2.8.6.
I tested it on a standard (not MU) site running 2.8.6 and it works fine.
I am logging in as a Site Admin, but I have also tried it as a non-site admin user who is an administrator of the blog. I have tried it in blogs where my site admin user is an administrator of the blog and not a user of the blog at all.
Any suggestions?