Although its trial restriction keeps it from being a comprehensive solution, this Registry optimizer offers a nice degree of user control over the cleaning process. Registry Clean Pro's main window is no work of art, but we appreciate that it walks you through all processes with step-by-step wizards. The program lets you schedule cleaning sessions on a daily, weekly, or monthly basis. We also like the real-time detection feature, which immediately alerts you as soon as the application finds a Registry error when running in your system tray. Similar to most good Registry tools, this one allows you to undo any changes you've made, although it doesn't immediately back up your Registry before removing entries. We also wish the app offered more information on whether it's safe or potentially harmful to remove a certain key. The custom-scan option lets you choose which areas of the Registry to examine, including shared DLLs, fonts, and application info. However, since the trial version won't let you remove bad ActiveX controls or file extensions, it won't get your Registry spic-and-span unless you're willing to drop the cash. Still, the app offers enough functionality to make it a useful pick for more seasoned PC users who can identify invalid keys without much assistance.