Thank you Ken!

I think I included all workarounds of getting the common Add-In
problems. And now I don't know how to make it better. (I checked the
code for so many times without finding an error)
My Add-In does a lot and maybe I have to live with problems, because
the whole COM thing is buggy and can cause many problems.

Another question:
Sometimes I have to depend on the error handling because some objects
are causing errors but only in really rare cases which I don't know.
(Normally I don't get errors, when I uncomment the error handling)
Although I'm using "On error goto... or ...resume next" an error
can cause an Outlook crash?