EDIT: THE LAUNCH SERVICES CACHE IN OS X WAS CORRUPT. POST 6 HAS THE SOLUTION IF ANYONE ELSE ENCOUNTERS THIS ISSUE! Original post: Ever since installing El Capitan (as an upgrade from Yosemite), I've had this issue. My system was pretty much completely clean apart from Logic Pro X and Dropbox, so I don't think it's a 3rd party utility. Symptoms: If I double-click a TextEdit document, nothing happens. TextEdit is not launched, and the document is not opened. If I "Get Info" on the file, it says it is associated with TextEdit. I tried to set it to another application, chose "Change All", and then set it back to TextEdit and chose "Change All". This temporarily fixed it. For a couple of hours, I was able to double-click TextEdit documents to open them in TextEdit, but then it stopped working again. Can't seem to find anyone else with this issue? Any ideas?