There seems to be a gmail bug in the latest version released. Sometimes it will not follow the backto inbox link or the inbox link when viewing a message and you must go back and try again.
This is in 0.9.12... There is an option to make it work again. There's a security flaw and, by default, settings are used to escape the flaw. These settings can have an effect on how a few Google products work, so go to:
(Tools > Privacy > Permissions > Google Maps/GMail enable/disable)
Make sure to set it back to make sure you are protected again after you finish using gmail.