Thank you for your report. The devs will definitely look in this. As you well know, Windows 10 is an ever changing platform until it is RTM. Being thus, it is piriform's usual position that a pre-release product (alpha, beta testers) is not officially supported until they go Gold. While, I believe, some of Ccleaner's change logs may mention basic Windows 10 support I'd still follow the advice that it most likely will have (major?) issues until Microsoft has released it.