I installed Corel Painter IX TBYB on my OS X 10.3.8 system. I then installed Corel KnockOut 2 (2.77 with 2.0c plug in.)

I set permissions to read/write for both folders and their contents.

I was able to repeatedly open photos in Painter, use the KnockOut plug in (which transfers the working layer to the KnockOut application,) process and apply - over and over and over. (The only bug I noticed was if I accidentally selected Quit from within KnockOut when it had been launched from the Plug in via Painter it would generate the "Unexpectedly quit" message. No biggee although it does make me wonder why the Quit option is there.

Next I downloaded this update titled Corel KnockOut 2.0 Update. It updated my version 2.77 application to 2.88.The plug in remains 2.0c. Upon launching Corel Painter IX again and attempting to use KnockOut, not much happened. Blue & white beachball cursor appeared. The program seemed frozen. Manually launched the KnockOut 2 application and my working layer appeared. I was able to edit but Corel Painter never regained its composure after the blue & white cursor had appeared - KnockOut was running but Painter appeared to be frozen. I quit both. I found and trashed all the KnockOut preferences & the application and plug in (and a temp folder in / which may have been Painter.) I also trashed the Painter prefs.

I reinstalled KnockOut 2.77 again. And it works again. Repeatedly, without restarting.