You mean just vanishing, and your desktop re-appearing? If you want solutions it would be best to give more information. Step-by step reproductions. Videos. Crash logs etc
Or you can just whine. FWIW, even though C6.5 was a very good version, however there were continual complaints about it’s stability, bugs, etc. It may be frustrating, but C10.5 plus earlier versions have generally worked very well for myself.