I often find that Painter does not relaunch after I have been using/ creating custom captured dab variants, and I believe it is related to a Tracker bug.
If you delete the Tracker Settings.xml file from the last User Workspace folder you were using (Default is the default user workspace folder name), you may find that you can relaunch Painter. A new Tracker Setting.xml file will be created automatically, and if it works, your custom user resourses/ other settings will be unaffected.
Default path to the Painter X/11 User workspace folder:
Mac - Users > [User Name] > Library > Application Support > Corel > Painter X/11 > Default [or custom workspace name]
Windows - Documents and Settings > [User Name] > Application Data > Corel > Painter X/11 > Default [or custom workspace name]
Windows Vista - Users > [User Name] > AppData > Roaming > Corel > Painter X/11 > Default [or custom workspace name]
I also use Time Machine to backup automatically to an external drive.
David