Can't get into store - "Fatal Error"

[Guest]

Hi folks,

 

Newbie here, please bear wiht me.

 

Did the install, set up some products to test it all, when I click "catalog" I get this:

 

Fatal error: Unknown(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition <b>navigationhistory</b> of the object you are trying to operate on was loaded _before_ the session was started in /home/kenpeel/public_html/oscommerce/catalog/includes/application_top.php on line 309

 

There was also something about php.ini - but I don't get that anymore (where's php.ini ...?).

 

Help!