Thanks Mylenium. Without luck, I'd already tried disabling updates from within the apps themselves during their successful first run. Per your note, I then deleted the Registry startup entry "AdobeAAMUpdater-1.0" and rebooted - that also didn't prevent the problem for me. However, I've since blundered into the following work-around, that seems to be OK for me, though I'm still unsettled as I have no idea about the root problem. Adobe Tech Support seems aware that their is a real probelm in the field with this, but hadn't yet (as of last week) nailed it down enough to release a substantial answer.
1) Renamed the two instances of "updaternotifications.dll", for Dreamweaver CS5 and Device Central CS5. (Device Central CS5 exhibits the same run once then fail forever symptoms.) These two dll instances are:
\Program Files\Adobe\Adobe Dreamweaver CS5\updaternotifications.dll
\Program Files\Adobe\Adobe Device Central CS5\updaternotifications.dll
This solves the crash on start problems, but leaves me with inactivated "Update Now" menu entries in the software.
2) To search for patches on demand, I can run the updater manually by executing the file:
\Program Files\Common Files\Adobe\OOBE\PDApp\core\PDApp.exe
I used this to successfully retrieve updates I knew where out there, after disabling the .dlls.
Thank kindly for your attention, Cheers, BobH
Answered to the degree I have a work-around for the nonce. Forum traffic seems to indicate this problem, though obscure in root cause, crosses all manner of CS5 products. Updaternotifications.dll is itself crashing, the first time or two of each install with crash-notification to Microsoft. Even if the environment surrounding the dll (priveleges, file ACLs et al) were less than ideal, I don't believe it should just "Crash". And to the best of my knowledge, I'm "clean" relative to all the ideas I've seen forwarded: have admin rights, file ACLs are correct, AV and Firewalls not intruding, no special security restrictions... Seems to me to be an old-fashioned bug, though probably obscure and relating to or interacting with the overall system configuration.