I had a weird experience with Firefox 3.0.8 on my Vista Ultimate machine today. I had left one tab open while doing something else, and the theme had somehow switched over to the XP one when I checked next. Everyone who has used Firefox 3 on Vista and XP will be knowing that the default theme is different for both OSes. 

I’ve got screenshots as well -

And no, I’m NOT using the “XP on Vista” theme!

The theme was back to normal after one restart.

I don’t know what caused this, so if you’ve got some ideas do enlighten me.

:)