Sounds like launchservices database needs rebuilt.
Create an applescript by copy and pasting the script below into your Script Editor. Then run the script.
set theCommand to (do shell script "locate lsregister")
set theArguments to " -kill -r -f -domain local -domain system -domain user"
set thePath to " /Applications" --edit this as needed
set theScript to theCommand & theArguments & thePath
do shell script theScript
That's a lot of mucking around, when this command (all one line) in the Terminal app does the job nicely:
*/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchS ervices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user*
Darn ... I thought for sure that would have solved the problem. The outcome would be that your apps would launch properly.
It seems like you may have some directory or permissions issues. Try repairing permissions with Disk Utility in Utilities>Disk Utility. Also, run the Verify Disk to see if the disk and directory have any errors. If they do, you will have to reboot from your original system disk and run Disk Utility from there to repair them.
Ok. Repaired my disk. Repaired my persmissions. All's well except that Mac Help won't run and my other apps (chess.app, front row.app, ichat.app) are still looking defunct.
How should I be thinking about repairing the problem now?
THanks, by the way; I really appreciate your insights.
Download and install the 10.5.6 COMBO update, repair permissions, and restart. If the problems remain, do an Archive & Install installation, saving user and network settings, as described in http://support.apple.com/kb/HT1545