WordPress MU

I have WPmu installed and working nicely except one thing: when I try and edit the blog settings (wp-admin/wpmu-blogs.php?action=editblog&id=1) I get a 400 Error whenever I press the "Update Options" Button.

I notice that the page that gives the 400 Error is "wp-admin/wpmu-edit.php?action=updateblog" there is no "&id=1" on the end. If I add "&id=1" to the address and resubmit, I get a page with a box containing the text "Are you sure you want to do this?" - but there are no buttons to go on from there.

Any suggestions as to why I'm getting this error?

Still can't get this to work. Anybody have any suggestions at all? I'm guessing it is a server problem or maybe something in the .htaccess file...

Resolved - needed to get my web host (JodoHost) to add mod_security exclusion rules.