The code statement....
if (Profile.SCart == null)
appears more than once on the page in your link.
There is thread there already outlining the same problem you mentioned.
The author states he is implementing AJAX extensions,
Do you have those installed?ALSO ALSO - Probably the BEST solution!!!
Who ever the author of the article is....
He/She has offered to look into the issue if your send your source code to him/her.