Q: Mavericks Calendar shows on-screen but is not running, spinning beachball....

it happened because there was a problem with the application, problem with another application or an incompatibility with something in your computer as a whole

it happens to millions of computer users every minute of every day, and it's probably the reason I sit at a desk now instead of recommending a delightful Napa pinot noir to go with that braised elk in Armagnac demi to a diner.

if you would like further investigation of this phenomena you can post a log file from the session time this happened by going to the console and including the log information pertinent to that time and to borrow a phrase heard on these forums in this event please do not dump thousands of lines of code indiscriminately into the post, just those that pertain to this event. This can be found in the console app in your Macintosh HD/Applications/Utilities folder

you can also clear the log, the open the calendar and attempt to reproduce this if you can not pinpoint the event in the console.

if you would like an analysis of your system you can also post an etrecheck report (www.etrececk.com) in this thread as well.

Etrecheck – System Information

Glen, I don't know if any, but my experience with Calendar is very limited, it only reminds me of things I have to do that i don't want to.

but the console may give clues as to what caused it and if you can reproduce it then it may be worth reporting to Apple. If it was a simple "I was using it and it crashed" it may be more difficult to determine the cause but the usual offenders we see around here are any 3rd party mac utility that makes claims of "clean" or "keep", etc. - these are notorious crap ware titles that brand themselves as performing some necessary function that OS X already does do and with great ability (the first five minutes of Pixar's "the incredibles" will explain better than can: OS X does not need sidekicks), also high on the list of offering software seen here are commercial Anti-Virus titles for Mac. Mac AV IMHO has not had the opportunity to mature with the OS, lacks the developers, lacks the corporation with Apple and lacks a necessity at this time. In many cases running an AV on a Mac has shown to be disturbingly problematic and many here will recommend you remove one if you have it. Aside from those it could simply be another application caused a problem, or Calendar does have a bug that is not widely reported (at least not to me.)

if you want to continue posting your findings then myself and others can lend further suggestions and opinions to try and help you out - at least until I sneak out of here and go prime myself with beer and chennin blanc popsicles for the 4th of July weekend.

Try posting the Etrecheck report in case the problem is a 3rd party application.

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Quit the application.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J.  When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder.  Select Library. Then go to Preferences/com.apple.iCal.plist.  Move the .plist to your desktop.

Restart the computer, open the application, and test. If it works okay, delete the plist from the desktop.

If the application is the same, return the .plist to where you got it from, overwriting the newer one.

Thanks to leonie for some information contained in this.