Nothing jumps out at me except...!
Installed Combined Community Codec Pack
What did you do this for?
I install CCCP by default on all new systems, so I never have to see a "missing codec or plugin" warning again.
Installing Bulk Codec Packs has been an issue of many systems around here.
Do a little search in this Forum eg "CODEC PACKS"
Can you try uninstalling it and see how things work for you. Common advice and wisdom seems to be that it is difficult to do and often requires a reinstall of the O.S as well as the Adobe software. Hope thats not so for you.
http://forums.adobe.com/search.jspa?resultTypes=DOCUMENT&resultTypes=MESSAGE&resultTypes=C OMMUNITY&resultTypes=TASK&resultTypes=PROJECT&resultTypes=SOCIAL_GROUP&resultTypes=COMMENT &peopleEnabled=true&q=codec+packs
Compliments on a well documented question and a good analytical approach to solve the issue.
Craig is right with the CCCP.That is almost certainly the cause of your problems. The downside is that it will possibly require a complete reformat and fresh install of OS & programs to get rid of it.
In general, NEVER install codec packs, unless you are absolutely sure that that codec is needed and is well known not to cause problems. If you still experience missing codec messages, then either use other material that is suitable for editing or convert externally and accept the inherent quality hit. Also realize that websites that offer codec packs, may have very positive reactions from users but those reactions come from playing not editing. The list of reliable codecs for CS5 is very short and are usually oriented towards visually lossless codecs that use a lot of disk space.
CCCP is certainly a possibility, but I've used Premiere CS4 on a workstation with CCCP and had no problems. It's also very clear about exactly what it installs and why, and it's all pretty innocuous stuff.
But I'll pursue it; I already uninstalled it, but I'll step through its install file-by-file and make sure it really is gone.
Obviously, the simple solution would be reformat/reinstall, but I'm struggling like a fish on the hook to avoid that misery if at all possible.
Thanks for the help, and let me know if you guys think of anything else to try!
Like Haali and FFDShow, both have been known for extensive damage to a system.
I admit I don't know whether sensitivity for these codec packs has increased from CS4 to CS5, but they have always been infectuous and are better avoided.
It was an inadvertant fix so I failed to properly document it, but as far as I can tell, it was this:
The "My Documents" shortcut under Windows 7's 'Library Locations' was pointing to a folder that no longer existed.
As soon as I deleted that shortcut, Premiere gave a "could not find Documents folder" error on startup, but then started up successfully!
I then created a new "My Documents" pointing to an actual folder, and now PPro is happy.
There was a similar thread over in the Elements forum recently, where laptops connected to a company network that used redirection to point "my documents" to a network drive would not let Elements start when the laptop was out in the field
It appears that Adobe's programmers have hard wired a file location into all flavors of Premiere, and if the file location is not there, the program won't work