It seems that you are running XP and you disabled the old messenger that came with XP before installing the new versions. Some user reported that in this thread, or was it by mail? I'm not sure, but you can look. Anyway, if i remember correctly you can disable the old messenger, but you need to install the new versions first in order to avoid that question about messenger.msi everytime you open it. The tool from benner does not do anything special in this regard, so if you use it you will face the same problem. Please report back if you solved this. I found that this happens only if yo have an old version of MSN installed and than removed like you said. With a clean system no errors.