Getting Error [HTTP/1.1 405 Method not allowed] after “Subscribing to Posts”

I’ve searched the forums and this discussion – so far no one else seems to have this problem.

– Post_Notification was successfully Activated
– Post_Notification was successfully added to my META links
– Post_Notification can successfully send a TEST mail
– Post_Notification does show the “Subscribe to Posts” form
– …however when the user enters their email and clicks SUBMIT, they get the error [HTTP/1.1 405 Method not allowed].

Please help!

BTW – Here’s my system info:

– Windows 2000 Server
– IIS 5.x
– PHP 5.x
– MySQL 5.x
– WordPress 2.3