beagle1957

OK, I finally got CCleaner 5.42 to work, but the solution was a bit complicated: Apparently, it is the combination of Kaspersky patch (g) and the Windows 10 April Update causing the issue with CCleaner 5.42 on my system, at least.. I restored a system image I created with Macrium Reflect Free on 4/29/18, BEFORE the Windows 10 1803 update. The image already had Kaspersky Internet Security 2018 patch (g) and CCleaner 5.41 on it. I updated Kaspersky to patch (h), then updated Windows 10 back to 1803. Finally, I updated CCleaner to version 5.42 and it no longer crashes on clean. It would be interesting to know the order in which users installed the Windows 10 1803 update, CCleaner 5.42 and Kaspersky path (h).

I was actually referring to Piriform testing 5.42 on 1803 rather than end users. Just FYI - Kaspersky just issued path (h) for Internet Security 2018. I installed the patch, rebooted the PC and re-installed CCleaner 5.42. Unfortunately, 5.42 still crashes on clean but without the error message. Uninstalled 5.42 using Revo Uninstaller to wipe all traces of it from my system. I found a suitable alternative for CCleaner which I will use until Piriform releases the next version (which hopefully fixes this mess!).

OK, I have Kaspersky Internet Security 2018 with patch (g), updated to the latest definitions. CCleaner 5.42 WORKED on my system with Kaspersky UNTIL my Windows 10 Pro got automatically updated to the latest version 1803, and THEN it started crashing on clean. Per Stephen's suggestion above, I tried uninstalling/reinstalling Kaspersky after the Windows update (again patch (g) with the latest definition updates, and 5.42 continues to crash. Went back to version 5.41 and it works flawlessly. I have to ask this - was version 5.42 tested under Windows 10 1803 (the April Update)?