If, like me, you were using your own static homepage as described here:
under version 126.96.36.199 and found it disappeared when upgrading to 1.9.0/1.9.1 then I have a simple fix so everything will work as it did.
I tried all the suggestions and could not get what I wanted. The workarounds did not result in what I initially had. So after countless hours of pulling my hair out, I finally got it to work.
All I needed to do was add a modified front-page.php to my child theme and update the custom CSS from that link.
You can see how I am using the theme here . I am just using it as a normal blog, and only wanted that theme because it is suitable for multiple devices (responsive).
If you want to try upgrading and get your site to stay looking the same, then the file and CSS can be downloaded here.