h261rend.dll belongs to the plug in for RealMedia Player. If you don’t use RealMedia Player, try uninstalling this software entirely. Even if you are going to use RealMedia Player, it would be a good idea to uninstall it completely and then to reinstall it properly.
This type of message has much less to do with a media player and much more to do with a clogged registry. The Windows registry is a bit flawed in its ability because files can make their way through its loopholes and onto your screen. While the Windows registry doesn’t contain malware, the very design of a registry allows malware to penitrate.
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