I just downloaded and installed (allegedly successfully) Joast's awesome looking plugin for SEO. After it has installed I got the following error message when trying to click on any area within my WP Dashboard and also when I or anyone else goes to my site http://www.mypcos.info.
Fatal error: Call to undefined function get_queried_object() in /home/mypcosi/public_html/1/wp-content/plugins/wordpress-seo/frontend/class-frontend.php on line 354
Unfortuanately I don't know what version of WP I am using (sorry, I know how terribly unhelpful this is, but I can't go in and check now!). It's not 3.3.1. I haven't updated it for at least one and maybe 2 years now. I suppose this is likely to be part of the problem.
Do you have any idea how I can fix this? I don't have a technical background and haven't got a clue where to start.