Spinning wheel after upgrade

[nexusxox]

I recently was asked to check a computer that a user recently upgraded and ever since the upgrade he is getting a spinning wheel. Are there any suggestions on what to try to correct this issue. Its a MacBook Pro and I believe it had Mountain lion and was upgraded to Maverick

 

[gsahli]

First thing I'd try is a Safe Boot. It does some repairs in the background and therefore is slower to start up. After it's done, note whether it still does the same thing, then boot normally and check there, too.
OS X: What is Safe Boot, Safe Mode?

Be sure to tell us Mac model number, OS X version and free hard drive space in reply.