I have been having a similar problem (Symantec instead of McAfee, hlpoj.dll instead of msephh.dll), for about a week now and just ran across this thread. Thanks to all who posted suggestions of things to try. I ended up booting off the install CD, running the recovery console, removing the offending file.
To keep it from coming back, I copied another system dll file to the name of the trojan/virus one, and used "attrib +rsh".
If you (original poster) can get your hands on an install CD, or use one of the other methods of removing the file, perhaps this will work for you too.
Good luck,
Nathan
