I recently switched back to Thunderbird from Outlook for various reasons and I ran into a annoying little thing. When replying to a message the cursor automatically goes to the bottom of the message, under the quoted text. I found this really annoying because it means you have to read or scroll past all the parts of the previous conversation before getting to the new part. After a little bit of messing with the settings I found the solution.
I use multiple browsers on a daily basis either because some sites work better in some browsers versus others or to test web applications, etc. Typically I prefer Chrome over any other browser but sometimes I use Firefox because of some of the plugins available. Sometime in the past the Firefox installation on my Windows 7 Ultimate 64-bit laptop became corrupted so when I attempted to launch Firefox it would flash for a moment in the taskbar and then close immediately. The Firefox window would never display on the screen or even attempt to display on the screen however you could see the process for a moment in the Windows Task Manager as shown in the below image.