MultiZilla tab closing error!

Whenever I try and close a tab, this error comes up in the javascript 
console, and it *won't* close the tab, despite the fact that it worked 
fine before. The strange thing is, you can usually close 'middle' tabs, 
but NOT the first-opened tab, or the last-opened tab.
This appears to be in both the 1.5.0.2 and 1.5.0.3 versions.

Error: tabbarVisibilityBroadcaster has no properties
Source File: 
chrome://multiviews/content/bindings/tabbrowser.xml#tabbrowser.setStripVisibilityTo()
Line: 3