Users widget

I have manage to get Users widget to be a default widget when a new blog is set up.
The new blog is created and the rest of the sidebar menu items display. But where the widget should be I get an error message.

However, it seems to have some problems with line 156
Returning this:

// Warning: Invalid argument supplied for foreach() in /home/fhlinux130/f/ on line 156 //

This line reads // foreach ($users as $user) { //

Have melted my head trying to work out whats happening.

I would be grateful if someone could help me resolve this.