I'm running a fresh install of Ubuntu 11.10 running Gnome Shell, everything working as it should.
I just installed Midori from regular Ubuntu repositories using Synaptic Package Manager, but when l attempt to launch it, despite the appearance of the Midori icon and the "whirl" in the top panel, the browser does not start. Switching GUI does not change the effect.
As requested, starting Midori from the terminal generates the following output:
giulio@giulio-laptop:~$ midori midori: symbol lookup error: midori: undefined symbol: webkit_web_view_get_selected_text
Use these to remove the old midori package and install the new package from the
midori
ppa:You can also use the updated webkit package from the unstable webkit ppa.
(converted comment into answer)
This error message was reported in this RedHat bug-report.
Specifically it mentions an incompatibility between a similar version of Midori used in Oneiric with an updated (v1.6) of libwebkit. I note that Oneiric uses version (v1.4).
In your comments you mentioned you are using the WebUpd8 PPA that upgrades libwebkit. Obviously you now have a conflict between package versions.
Fixes are available for midori - but you'll need to compile from GIT to obtain these - as yet, the Midori PPA doesnt have this fix.
Alternatively consider
ppa-purge
the offending PPA. Down-grading your libwebkit may fix your Midori issue - but most probably will break whatever PPA application that required the updated version of libwebkit.