PayToBlog: Can't update Settings

Hi,

When I try to save new paytoblog settings I get this msg:

Permission Denied
Not Found / No Access
The page you are looking for either does not exist, or you do not have the permissions to access

In the WPMU DEV section of the dashboard it says I'm at release 1.5.6, yet under the Plugins "Must-Use" it is listed at 1.5.2. Not sure if that is significant.

So I reinstalled 1.5.6 putting the folder into .../plugins/ and pay-blog-paypal.php into the putlic_html folder. When I do a Network Activate I get this error:

Fatal error: Cannot redeclare pay_to_blog_modify_menu_items() (previously declared in /home/mywood/public_html/wp-content/mu-plugins/pay-to-blogSAVE.php:40) in /home/mywood/public_html/wp-content/plugins/pay-to-blog/pay-to-blog.php on line 87

When I look at the WPMU DEV it shows the plugin as installed at 1.5.6.

Any advice?

Larry