Problem using v 1.6.1 with PHP 5.4

Just upgraded to PHP 5.4 on the server. My Elgg site (http://gardenerschat-shed.net) now shows this error message:

"Warning: Creating default object from empty value in /home4/scc123/public_html/gardenerschat-shed.net/engine/lib/elgglib.php on line 1484"

Is there a way of rectifying this problem by editing a script file in the Elgg software - without the huge pain in the arse of going through a labourious upgrade to the version I use?

Many thanks,

G.