Platform is OS X 10.5.
I got the 2.2.6 binary from the official link (link on amule.org to the pre-compiled package in this forum).
When I downloaded and copied the files from the disk image to the applications folder I was logged in as admin.
When I started amule I was logged in as user without admin rights.
I was asked for admin name and password when starting 2.2.6 for the first time (I got the message "You are starting amule for the first time").
I had not deleted the amule files from the application support directory.
It was the standand system panel and it appeared 2 times (I refused, then it appeared again, again I refused, then it didn`t show up again).
Meanwhile I also copied back the original amule files (amule.conf etc.) which I had used with 2.2.5 (which did not porperly start in the end) and tried starting 2.2.6 again. Still the same: 2.2.6 crashes on startup.