I believe I have ran into this exact issue. Your plugin appears to be unable to access its own table in the wpdb to grab a verb to use. Not being any good at php, I decided just to replace the error with defining a single verb to use which allows the plugin to finally work.
Unfortunately the problem is much more than I thought. If I place this widget above another one, like the RSS Widget, the entire site will go blank on me. Only if this widget is placed under the RSS Widget will the site continue to function. If I place other widgets like a custom one that only displays an image, or the regular Meta widget below this one, all is fine. Now I assume this is because the RSS Widget accesses wpdb.
I don’t know crap about php, but I do know a serious problem when I see one. The only work-around I can think of is simply merging the killboard and wordpress databases.
