Microblog not working

I only want the first level of subcategories to show on the categories page: http://thenag.us/topics

When I try to post a microblog, it does nothing, and when I click on "Click here to set up autopostings" I get this error:

Notice: JFactory::getUser() [jfactory.getuser]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "CUser" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /home4/answerit/public_html/libraries/joomla/factory.php on line 244

And I'm getting this error http://thenag.us/topics/nag-invasion

Notice: JFactory::getUser() [jfactory.getuser]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "CUser" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /home4/answerit/public_html/libraries/joomla/factory.php on line 244