I had a similar problem when I migrated a site and upgraded WP. I dumped the site’s database into a new one with the current copy of WP, but when a certain user would install, activate, or de-activate a plugin, the plugin area and even the entire admin area of the site went white.
What I noticed is that the problem came up when only a certain user worked with the plugins, not from the new user that I had created for myself after migrating and updating the site. When I re-created and deleted the corrupt user, the problem went away.
If this is the same problem for you, be sure to watch out when you go to delete the corrupt user if all your blog posts are created under it. First create a temp user with admin privileges, transfer the posts to the temp user when you delete the corrupt one. That way you can re-create the corrupt user with the same name and e-mail and transfer all the posts to it by deleting the temp user.
