How to Clean Up a Windows 7 Registry
The Windows registry contains all of the system settings for your computer. You can clean up the Windows registry using the Windows System Restore feature, included with each version of Windows. This feature removes changes to the registry from software or viruses that slow down the computer.
Click the Windows 7 "Start" button and type "system restore" to open a list of Control Panel utilities. Double-click "System Restore" to start the Windows 7 wizard.
Click the option labeled "Choose a different restore point" at the bottom of the first window. This option lets you manually select a date to roll back the registry changes.
Choose a previous date to roll back the registry changes. Choose a date at which your computer ran more efficiently. Click "Next."
Click "Finish" on the final screen. The registry restores to a previous date and any malware or affected registry entries are cleaned.