Beginning early this past week sometime I noticed the right-click context menu in Firefox opens with the mouse pointer right in the middle of it. As a result it usually selects "Inspect Element" immediately, when what I want is to select "Search Yahoo for 'selected word'".
This doesn't happen when using Chromium or Chrome on the same computer and same user. I reset Firefox, but that didn't fix it. I removed Firefox and and the .mozilla folder from my home directory, then reinstalled Firefox and tested before syncing with my Firefox account. It still behaved the same way.
I created a new user in the OS and tested with the same results.