There is a known issue with the popular Firefox extension Adblock. It seems that when you have Adblock installed and enabled, the video window in the left panel becomes off-center and receives scroll bars. See below for an example of this effect.
If this is interfering with your use of email2, you can easily disable the display of the Adblock tab without disabling or uninstalling Adblock itself.
When Adblock is installed, an Adblock Plus (ABP) is added to your toolbar. It looks like a red stop sign. When you have located this logo, click the 'down' arrow directly to its right. From the menu, select "Options" and then uncheck "Show tabs on Flash and Java". The image below describes this process.
