Firefox 3 and extension(s) problems

Well, we all were waiting for it...Firefox 3 to come out of beta.
And so it did. Yes, it loads faster and doesn't use quite as much RAM.
Those aspects are of importance to me.

But, and you knew, that it was coming, what is up with the extensions?
I used to have 40 + in my FF 2 installation. Now I can't get more than
15 extensions to load and function. I even have an RSS feed with the
latest extensions info and they don't load either; they are either rejected or installation fails.

I must admit that I run FF 3 in a sandboxed browser (sandboxie.com).
But, that has never made a difference before.

I read some of the daily FF oriented blogs and can't find anything
written about extensions and related problems. Also, I receive a daily google alert
related to extensions and associated problems - nothing there either.

What's been your experience?