From time to time the “Open With” option in OSX will get out of sync and begin showing duplicate icons or even start a different application than expected. Installing, removing or updating applications often causes this. On the Mac the associations between applications and file types are saved in a database called “Launch Services database”. Luckily it’s relative easy to fix this problem by rebuilding the database.
On most installations of OS X 10.5.x and later you can rebuild the database by running a few simple commands from “Terminal”. First open “Terminal” (If you don’t know how to open “Terminal” hold down “Command” and press “Space” once, type in “Terminal” in the text field that opens and chose the “Terminal” app). Copy the following code to the command line and hit enter.
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/
.framework/Versions/A/Support/lsregister -kill -r -domain local -domain user; killall Finder;
The Mac will then rebuild the database and restart “Finder”. This can take anything from a few seconds to several minutes depending on your system. When completed the “Open With” option should be up to date. That’s it!
Several other websites recommend the OSX utilities Cocktail and OnyX if you fell uncomfortable working with the Terminal using raw commands. Besides fixing this problem they also provide several other options for adjusting and tuning your Mac.