The [shift] behavior occurs in the yahoo mail password box. It takes me to the previous page as soon as I depress it. Same with both [shift] keys. I use the [shift] for "W" and "+" in my password.
HP 2000-2c23dx, Win 8.1 Update. Windows updates current. HP updates current, and Firefox 31.0. In Firefox, I do have NoScript and Web Developer.
Thanks in advance.
Here are the list of shortcuts on the Yahoo mail: https://help.yahoo.com/kb/mail-for-de.../keyboard-shortcuts-overview-sln3578.html
It does not look like it is one. Can you please check to see if this happens in Safe Mode? Troubleshoot Firefox issues using Safe Mode If it does not, it may be one of your add ons.
Did you try to reboot the computer or check for other issues with the keyboard?