That warning screen is normal on an n9 that has been repartitioned and/or had its kernel replaced with a non-official version. It can be removed, but that must be done before you do the flashing. This process is detailed in many of the flashing guides, but I'm not sure if it's in the Sailfish instructions.

You'll also find your password caches in Harmattan aren't working properly after this. Could be the cause of the crashing. Or the repartitioning could mean you're short of storage space, or could have adversely affected the harmattan filesystem.

Anyway, the solution is to re-flash the n9 back to the standard partitions and kernel. The warning will go away, any filesystem problems will go away, and you can prepare properly for another sailfish install if you want to try it again.

See here: https://wiki.merproject.org/wiki/Nem...ur_N9_firmware