This problem for most users was fixed with the 1.9.7 version of the firmware. You should contact Kobo Customer support so they can determine why the firmware is not working for you.
By Email
Email Kobo anytime, 24-hours a day at:
help@kobobooks.com
By Phone
Kobo Help Line, United States and Canada:
1-866-204-4714
(8am - 12am EST)