Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a

Hello,

I have just gone to click on my "home" button in my custom menu widget and have got a warning that's replaced all the menu items instead!

"Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'Array' was given in /home/designwe/public_html/taylormadepine/wp-includes/plugin.php on line 166"

My site is at http://designwebs.co.uk/taylormadepine/

I have tried dragging the menu widget away and putting in a new and still have the error showing. Any help will be appreciated.

I am using the latest wordpress and marketpress volume (in fact just updated the marketpress and now have this problem).