Very Good but now problem Rated 4 out of 5 stars

Very good addon but since ff15 I get this popup Alert:
JAVASCRIPT application: Type Error-Can't access dead object
It occurs for many others:
It occurs when I close the first tab.
It will keep popping up in an endless loop, and I cannot click on anything else so I have to close firefox through the TaskbarManager "End Process".
If I disable this addon then there is no more of this popup. So this addon is the cause of this popup.
Please fix.