I have same problem on CCleaner 5.42.6495 on W10 64. Just started yesterday. CCCleaner launches, but when I run "run cleaner", get the windows message "CCleaner has stopped working. A problem caused the program to stop working correctly. Windows will close the program and notify you if a solution is available"
I also have Kaspersky Internet Security. Tried uninstalling and reinstalling CCleaner. Ran avast uninstall just in case avast got installed with CCleaner causing a conflict with Kaspsersky. Restarted. Made sure Kaspersky definitions database was all up to date. Then reinstalled CCleaner again. No luck. Weird. Have been using CCleaner over a decade and this is the first time I've had a problem.
