When I right-click on a file on my Mac OS desktop and then in the contextual menu, I move to the "Open with…", the list of potential applications to "open with" has applications listed multiple times, sometimes three or four times, right next to each other!
- Why does this happen?
- How do I fix it?
- how do I stop it from re-occurring?
See this snapshot of the contextual menu showing the doubling up:
Now I have Mountain Lion on a 13" MacBook Pro, but this problem existed before I upgraded to Mountain Lion.
Best Answer
This happens because the LaunchServices database gets corrupted.
To fix on Mountain Lion:
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user
This command has changed over the years, but I just recently ran the above to fix the same issue on Mountain Lion. This hint on Mac OS X Hints covers the command for other Mac OS versions over the years.
If you don't like using the command line, the free tool Onyx also has an option under Maintenance -> Rebuild -> launchservices will work too.
As for how to stop it, I really haven't ever seen a way. I am not sure what actually causes it to corrupt other than I know it is very actively used.