BetterPrivacy 1.25 error in Firefox 3.0.8

I’ve had to temporarily disable the BetterPrivacy extension because since I upgraded to Firefox 3.0.8 I get the above error message every single time I close the browser. Upon clicking it, all the browser windows disappear but Firefox stays active for anywhere between 5 to 30 seconds in the dock before finally quitting. It’s quite irritating!

Given it’s a JavaScript error I suspect perhaps it’s having a conflict with NoScript but disabling that extension still renders the above error. I’m running Firefox 3.0.8, BetterPrivacy 1.25, NoScript 1.9.1.6, Cookie Monster 0.97.0 and SSL Blacklist 4.0.30: as far as I know all the latest versions.

The error mentions NS_* (stands for NeXTSTEP, what Mac OS X was built from) which leads me to believe it may be a local problem. Anyone else having this issue?