Getting error I do not understand?

[richardd]

I am getting the following error and hope someone with better skills wil understand how fix it;

Fatal error: main() [<a href='function.main'>function.main</a>]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "navigationHistory" 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 /home/rdied/public_html/includes/application_top.php on line 312

Please advise

[MrPhil]

Search for navigation 312 and you'll find lots of discussion on this bug. Some people offer code fixes that supposedly cure it, while others just advise you to clear out (or let expire) your session information. Unfortunately, I've never seen an authoritative source bless one code fix, so you may have to try several fixes to see if one works for you.

[richardd]

Thanks much will search