I have the exact same issue on multiple servers and instances of JoomSEF installations. it has to do with it SEF'ing the admin URLs. it also affects module editing.
I reported it here:
www.artio.net/support-forums/joomsef/com...-html5-w3-validation
but no one ever replied.
"also, since I am posting anyway, since sef4 I notice I have to disable the 5 artio plugins in admin or I cannot edit articles or modules because the urls are sef'd with a bunch of & in the urls. i have used joomsef for a while and never had that problem until sef4 and now it happens no matter what server I am on so i don't think it is a server issue. but I just disable the plugins do what I have to do, then enable. however if this could be fixed it would be much better. is that something in the paid version maybe?"
My solution for anyone interested is to go to plugins, filter by artio, disable them all, then edit, then re-enable. this is very slow and time consuming and end user site clients don't love it either.
I understand this is "community" support -- but it would seem like answering on obviously buggy issues would be good for all.
