On 8 Aug 2011, at 02:49, Hao Ren wrote:
[…] Could you please tell me how to fix it?
Often when there are problems “talking to programs” it has to do with a corrupted launch services database.
You can rebuild it by running this (single line) in Terminal: /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill