recommend that tool to clean registry of old installations?

What are you cleaning? The best tool is the installation media. I'd clean install and restore from backup.Regards, Dave Patrick .... Microsoft Certified Professional -Microsoft MVP [Windows]

Software that was installed before and do not delete

These may help. If not I'd contact the application developer.How to resolve Common "Windows Installer" Problemshttp://support.microsoft.com/kb/555175Use the Windows Installer CleanUp Utility to remove Office 2000, Office XP, or Office 2003http://support.microsoft.com/kb/290301Regards, Dave Patrick .... Microsoft Certified Professional -Microsoft MVP [Windows]

Hi, Personally I don't recommend a Registry Cleaner as the results may have false positive. As Dave has suggested, you can use Windows Installer Cleanup Utility. This utility can remove installation information for programs that were installed using Windows Installer. When you want to remove a program or software application which was not installed using Windows Installer, always use the Add or Remove Programs tool in the Control Panel. Doing so ensures that any registry items associated with that application are removed safely. If your computer encounters any performance issue or errors related to Windows Installer, welcome to post in our forum. We’d like to provide assistance based on your needs. Regards, Bruce