Houston, we got a bug!
And a solution too, luckyly. I do not why is it happening though, I have been trying to reproduce it in my installation but it was impossible for me. The only way to get your errors I think is that you created those sidebars with an older version of the plugin, long time ago, and you have been upgrading the plugin since that (you did it right, but the plugin doesn't).
Anyway, your sidebars names are breaking the plugin:
Moxtelell your sidebar is called øko brocolly. The char ø is breaking the plugin
Denis, in your case the sidebar is called hypnothérapeutes and the char é is breaking the plugin.
The bad news is that you can't keep those sidebars, so you will have to create a new one with the old contents and delete the buggy one. The other problem is that you cannot delete the sidebar, because of the name! What a cruel world. So the easy fix for you would be to downgrade the plugin to version 0.8.2
With that version it is possible to create sidebars with evil names, but you can also edit them (not delete them). So it is the easiest way to continue editing your sidebars.
In Custom Sidebars 1.2 I will try to fix this problem, so you will be able to upgrade again.
Cheers, and thanks for the feedback