Is anyone on this list experiencing crashes with Outlook viewing digitally signed emails when the public key cannot be found?
Nope, never have, never will.
Wrong place for you to whine about it though. support@xxxxxxxxxxxxx sounds more like what you need. Me personally, I can't care less about Outlook bugs.
And once you report the issue to MS, and wait for a patch, you could work around the problem by getting yourself an email client, which doesn't crash in that particular situation.
//Andro
-- Andrey Andreev University of Helsinki Dept. of Computer Science