Bug in selecting Web Browser?

[karlkras]

(Sorry for multiple post, this originally wound up on PHP Users which wasn't my intention)
NB 6.8 Build 200912041610

I prefer using Firefox as my browser of choice. Somehow my system browser was reset to IE and I wasn't aware. Noticed that NB was firing up IE when in context of web related services so checked out the option->general to find that it was set to <Default System Browser> which as stated above was set to IE.
So I thought I'd just set it specifically to Firefox in the NB options. But alas IE continued to open on Web related tasks. Going back to the General options I found that it was set back to <Default System Browser> and failed to persist my selection. Obvious work around is to reset the <Default System Browser> and it works, but this would seem to be a bug at some level in NBs?