My b2evolution Version: 2.x

Downloaded the latest version and installed installed fine up until I had to log in using the admin and password. when i try to log in i get this error after clicking the log in button :

Fatal error: Call to a member function on a non-object in /home/content/N/e/c/Necroscaper/html/inc/_main.inc.php on line 447

if I go to the homepage url i get this error :

Fatal error: Call to a member function on a non-object in /home/content/N/e/c/Necroscaper/html/index.php on line 59

Have I messed up somewhere not obvious?