Along with many many others I found Upgrading to Mavericks causes lots of problems (and down time) with CS6 Photoshop. If you are running Mountain Lion stick with it awhile longer. The two fixes for Mavericks is upgrading to 9.3 or better and the work around plugin from adobe listed below. The adobe plugin has to be re installed every time you upgrade mavericks! Drop it into the plugins folder in PS. Thanks for another bug ridden upgrade, Apple. You might as well be Microsoft.