Kicked out of admin after changing Smarty settings

[paulyd85]

Hi.

I've recently switched server and then upgraded from 1.7.5 to 1.7.6.1 and now I'm getting lots of weird issues.

If I try to change any of the smarty cache settings, I immediately get kicked out of the admin panel and can't access it unless I clear my cookies.

When I say can't access it, if I type in the admin url it gives me an error 404 and redirects to the front page.

After clearing cookies this completely resolves, but then if I change the cache settings it just does it again.

I also can't upgrade any modules whilst I'm in the admin panel and I'm not sure if this is related.

 

Anyone had this before?