Windows registry maintains lots of information about your operating system. For example, it records the installed software, whether or not the CDROM can play automatically, etc. Many softwares add some information into the registry during their installation, or change some items. Sometimes it will cause some problems. For example, some softwares cannot run. Perhaps it is because the registry is damaged. Therefore, if you have backed up the Windows registry, you can try to restore it. Maybe it can solve the problems.