Little information is available for the a4.dll error other than it is a module of a program running on your computer. With such unreliable data on this particular error message, there is a possibility that it may be connected with a virus. The easiest way to tell the difference between a virus and a legitimate Windows DLL file is to determine the location that a4.dll is running from.
Most computer users will not have the skills or time to do a search like this manually. The easiest way to find the source of registry-related error, check for the presence of others, and assess their security threat to your files all at once, is to have your computer scanned.
The next step is to use a registry cleaning software to clean and repair your computer’s registry. Just remember that not all registry cleaners work the way they are supposed to. Only ZookaWare PC Cleaner has a guarantee that they will fix 100% of your errors.