madog32 on "[Plugin: Download Monitor] sidebar error message"

I get this error message on single download page after category, any ideas why?

I'm using twenty twelve theme.

sbg_selected_sidebar a:1:{i:0;s:1:"0";}
sbg_selected_sidebar_replacement a:1:{i:0;s:1:"0";}

http://wordpress.org/plugins/download-monitor/