When your computer slows down enough that you notice it, when it starts giving error messages, when it keeps hanging, when you get system errors or even blue screen errors, it is time to look at reconstructing a corrupted registry. Sometimes DLL files go missing and then you cannot even start some associated programs. What happens is that when you keep installing programs and software and then uninstall them the registry entries are left behind. Occasionally the registry gets corrupted and then all these problems occur.
A corrupted registry needs to be fixed. If you do know enough about computers and Windows, you will be able to fix the registry yourself. You have to run Windows in Safe Mode on start. This will enable you to work with the minimum resources. Then you run regedit and try and fix the errors, providing you know what is wrong and how to solve the problem.
However, do remember to back up the files and changes that you make on another drive or external storage media so that you can undo the changes if they cause any problems or stop the computer from running. When you go to regedit, then click on File, you will find options to import and export entries. You should export the details of the actual status before you change something to a text file and then, if there is a problem, you can always import it back. It is important that you take the right steps for reconstructing a corrupted registry.
There are different ways of used backup methods. Some Windows versions come with automatic back-up systems. In others you can use the Recovery Console which comes when you try to insert the Windows disc into the drive. When you come to the recovery console option you should click on that and follow the instructions.
Before you attempt reconstructing a corrupted registry make sure that your system restore point is active and working. There are also many registry cleaners available, with varying feedback.