Can't Modify Anything in General Settings

For some odd reason, I can no longer edit anything in my General Settings in the admin panel. When I hit the Submit Settings button, it takes me to www.mysite.com/guestbook/admin.php but with an IE error HTTP Error 406 - Not acceptable and it's just a blank page. But when I refresh the page it takes me back to the admin login page.

Edit to add... I'm using 2.3.1 I didn't have this problem in the past untill my hosting company had troubles and had to reset everything. I'm hoping this is something that can be fixed in the database.

No suggestions?

This error occurs in Web browsers.
If the Web server detects that the data it wants to return is not acceptable to the client, it returns a header containing the 406 error code.

Use Mozilla or Firefox