I just moved some blogs over from hostgator hosting to our own web-server running IIS 7.5 and windows server 2008. All Blog run flawlessly EXCEPT I cannot add, delete or update any plugins on any of the blogs. I can however upgrade the blog version just fine after setting some permissions.
I receive an error like this when trying to update plugins:
You don't have permission to access http://www.domain.com/blog/wp-admin/update.php?action=update-selected&plugins=akismet%2Fakismet.php&_wpnonce=9b470d1831 on this server.
This happens on a single plugin update attempt as well as a bulk update on all update-able plugins. Oddly I get a similar error in phpmyadmin when trying to edit databases.
I have gone as far as giving all users all permissions on these blogs to test if that's the issue and still they throw the error at me. A blog I tested on IIS 6 worked though so I don't know what needs to be modified in IIS 7.5 to make wordpress play nice.