I just did a standard update of all programs on my computer (running Ubuntu 10.04), which included going from Firefox 12 (I think) to 14.0.1. Now I have an extremely strange problem - Firefox appears to be treating both my Shift keys as Alt: i.e. if I press Shift-f, I don't get an F in the textbox, but it selects the File menu; if I press Shift-1, I don't get a !, but nothing else happens; etc.
It's not happening in any other programs that I've seen (I checked terminal, pidgin, chrome). It's happening with both the laptop keyboard and an external USB one. CapsLock works as normal in Firefox; I can also paste the "missing" letters into textboxes without issues (which is how I'm writing this).
I created a new firefox profile with all extensions/plugins/languages disabled, and Shift still doesn't work.
Any ideas for why this could be happening or how I could find out? I've never done much firefox troubleshooting before. I haven't had any luck on google either, so apparently this is not a common problem. I don't know what else to do... (I'm not sure if this is the right place to post this question - suggestions for other sites are welcome too.)