After updating to Firefox 9.0 and subsequently to 10.0, I've run into a very frustrating and persistent problem with my spell checkers. The problem being, I used to alternate between a US English and a Finnish spell checker plugin, and this worked until the update to 9.0. Ever since, however, the browser only allows me to use one of the two plugins when both are installed. I have not removed, disabled, or in any way altered either of them and both still work individually if the other is disabled from the plugin menu.

As I type this, everything is underlined in red because Finnish is set as the default and the language drop-down menu doesn't let me change it, even though both languages still show up as usual. However, when I try selecting the one that isn't currently in use, it doesn't do anything. So the only way to change the language is to disable the other from the plugin menu and then restarting Firefox, which is obviously not the way it should be.