There are various ways in which we can classify. Major: A defect, which will cause an observable product failure or departure from requirements. Minor: A defect that will not cause a failure in execution of the product. Fatal: A defect that will cause the system to crash or close abruptly or effect other applications.
Auslogics Registry Cleaner is registry cleaner/fixer utility whose purported purpose is to remove redundant items from the Windows registry. The software helps to automate the process of looking for invalid entries, missing file references or broken links within the registry and resolving or removing them.
Removing or changing certain registry data can prevent the system from starting, or cause application errors and crashes. It is not always possible for a third party program to know whether any particular key is invalid or redundant. A poorly designed registry cleaner may not be equipped to know for sure whether a key is still being used by Windows or what detrimental effects removing it may have.