RSS Feed read incorrectly

There is an existing thread
http://wordpress.org/support/topic/174889?replies=8#post-871091
which has some answers but I still think there is a problem here.

The blog below should show 2 x RSS feeds one is ok the other isn’t. Does this suggest a different problem (in the thread).

http://toolbox.best-one.info/NewsB/

This is the error I get.

Warning: Attempt to assign property of non-object in
/home/ppppppppp/public_html/toolbox/NewsB/wp-includes/rss.php on line 440

I have around 10 similar feeds all created from same data and all just created in the last few days with Worpress v 2.6.2

some seem OK and some give the above error message.

The thread suggested inserting the code below. This code is already inserted in my installation

//if ( isset($rss) and $rss ) {
if ( isset($rss) && (is_object($rss) ||(is_string($rss) && $rss=unserialize($rss))) ) { $rss->from_cache = 1;
if ( MAGPIE_DEBUG > 1) {

I don’t understand too much about the files but I loaded rss.php into Excel and line 440 appeared to be checking for a cache file

Any help / ideas appreciated