Firefox 0.91+ teething problems

I installed the nightly build the other day on the pc at home and since then I've been getting a weird "Windows cannot find http://....." error message everytime I launched a URL. The ironic thing is that this was accompanied by two windows opening with at least one of them containing the url I typed in!
Apparently this is a bug that was meant to be fixed but JonGalloway et al beg to differ. The good thing is that there is a fix in the form of a reg file to download.
I'm also getting a number 1 appear in the bottom right of the screen - which is 1 new mail message - but on last count I've got 30+ unread emails in my inbox.
I also get a red exclamation mark which tells me that there are critical update(s) available when you hover over it - but when you double click and search for extension updates - there aren't any.
Still I guess this is what you get for running a nightly build.
0.93 and instructions are posted so i'll try that and see what changes.