With the install of 523 on 10/25, these error messages pop up in the event viewer each time CC is run...
455 ESENT: CCleaner64 (8020) testing: Error -1032 (0xfffffbf8) occurred while opening logfile C:\Users\<name>\AppData\Local\Microsoft\Windows\WebCache\V01.log.
489 ESENT: CCleaner64 (8020) testing: An attempt to open the file "C:\Users\<name>\AppData\Local\Microsoft\Windows\WebCache\V01.log" for read only access failed with system error 32 (0x00000020): "The process cannot access the file because it is being used by another process. ". The open file operation will fail with error -1032 (0xfffffbf8).
Restored an image of the partition from an era when, using an earlier version of CCleaner, no such error was evident. Then upgraded to 523-5808, which appears to be hanging while processing I.E.
That browser is never used, so all its options in CC were disabled. That appears to have put a stop to the error messages.