First the easy one:
After the PrPro CS4 4.1 update, a codec that had not been working in AME started working fine. Then suddenly one day, it was no longer working again. A post from Dennis Radeke on another topic recommended deleting the "4.0" folder from both AME and PrPro and restarting the computer. These are buried in:
C:\Documents and Settings\Administrator\Application Data\Adobe\Adobe Media Encoder
C:\Documents and Settings\Administrator\Application Data\Adobe\Premiere Pro.
Unfortunately, this is also where various keyboard customizations and preset customizations are kept, so deleting the entire folder wipes out a lot of things I wanted to keep, so I made copies of both of these before I deleted them.
After rebooting, I created a new custom preset and tried outputting through AME using the codec that had stopped working.
That was successful, so I then added my keyboard presets, etc., back into the 4.0 directory and tested export again. Also successfull.
I still don't know what happened to cause the problem, but I do know how to fix it if it ever stops working again.
The second success story is a little OT, but may be useful.
After doing some routine "housecleaning" to get the accumulated junk out of the registry, I decided to do a repair installation of the OS just to make sure that no relevant *.dll's etc., had been swept away inadvertently.
Everything completed successfully, except that embedded links in email would no longer open the browser, all links in "My Favorites" were gone, and many links on web pages would either do nothing or return the message:
"The Requested Lookup Key Was Not Found In Any Active Activation Context."
While my first thought was to reinstall Internet Explorer, left clicking on the Download button simply brought up the error message.
Thus a dilemma, how can I update the browser when I can't download the update? Use another computer? Try another browser? ...???
Online researches all said I should go into the registry and change some settings, uninstall, restart, reinstall, etc. but none addressed how to get the browser to reinstall it.
Then that little lightbulb went off and, revisiting the IE* Download page, I RIGHT CLICKED on the button which opened up the "Save Target As..." dialog. From there I was able to reinstall the browser with no problems, and now everything is working as it should. I even got all My Favorites back!
This is probably obvious to many of you, but I thought it might help someone with less experience.
And, FWIW, the whole system is running more smoothly, Premiere opens faster with no pauses in the "gas guage" when opening a project and I can Export through AME using my codec of choice once again!