Fatal error message on content > pages

[mosba]

Hi,

I am using 0.13 "Canary" on server with PHP 4.3.4, MySQL 5.0.22. Works with Apache/2.0.59 on Linux.

I am getting message:
Fatal error: Call to a member function on a non-object in ... /lib/classes/class.content.inc.php on line 2139
when trying to add content by clicking : content > pages (I dont run it in english so I dont know the proper items of menu. just guessing. it is simply where you see hierarchy of pages and add content itself).

The Line 2139 is in the middle of:      function & GetAllContentAsHierarchy($loadprops=true,$onlyexpanded=null)
that "Returns a hierarchy of nodes (ContentNode)"...

Everything else works fine and even this did work before. When it occured for the first time I doubleclicked on the link to pages because I was in hurry and it was loading somehow slowly. I would realy wonder if this caused the problem... but after first click it looked like the content was loading (just slowly) - and after the second click it kicked out the fatal error and keeps doing so.

Thank you for any help.
Jan