The most important reason your should fix Windows Registry errors as they occur is that this the one single preventative measure can greatly increase the life-expectancy of your Windows system by stabilizing the growth of its Registry.
Prevention is Key!
It is a fact of Windows that trying to fix Registry problems after they occur is much more difficult than preventing their occurrence in the first place. So when it comes to the Windows Registry, the motto should always be "prevention is key!" This is because it is often the most common and abundant types of errors that wind up killing Registries, especially those caused by a system's registered applications, users, and even Windows itself. As new applications are installed and old applications are removed, and as registered applications continue accessing and changing Registry data, they often leave small bits of themselves behind as orphaned registry entries.
By themselves, these errors will probably not reveal themselves in any degradation of speed or normal Windows functions, especially if your system is new. But if these errors are allowed to accumulate for a very long time, they can greatly increase a Registry's size and wreak havoc on the overall structure and stability of its database. And for a fast-growing Registry, even small error accumulations can quickly send your Registry's database structure out of control. If you don't fix these Windows Registry errors often, your system can very easily fall victim to sudden crashes, system stalls, or a severe decrease in operating speed. It is particularly at risk if you frequently install or uninstall applications and hardware, since these actions increase the Registry's rate of growth further by adding more registered components, orphaned Registry entries, and undeleted drivers to your system.