Where is the preference list for "open with" applications?
See the answer for Why does my Mac's list of “Open with” applications start listing the apps twice and sometimes three times?:

This happens because the LaunchServices database gets corrupted.
To fix on Mountain Lion:

Open Terminal.app in the /Applications/Utilities/ folder.
run /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user
Restart

This hint on Mac OS X Hints covers the command for other Mac OS versions over the years.