Hey FF,
Version 2.0.0.2? Interesting, I thought that the latest (non-pre) version was 2.0.0.1... may be using a pre release (I think.. not sure if you are using that or not..) might be a part of the problem?

Not sure what it is but anyways what does general.useragent.extra.firefox say? You probably checked all that, but I'm just curious. Oh and by the way you don't happen to have the useragent extension installed, which might have accidentally changed the useragent or something.. or may be its the websites themselves?