You should try to download process explorer from http://www.sysinternals.com/ and run that, the site also has several other applications for windows included in the ps-tools stuff. These applications will show you what is running at the time it is running, what is really running mind you, and it also shows you the actual tree of execution. This will show you where that iexplore.exe is coming from. Using this you can see whether or not it is the real IE. If it isn't (IE shouldn't load on startup, or unless you specifically tell it to) it will tell you where it is, delete(stop it from execution first) that one. If it comes back you have a virus, otherwise if it is the real IE, something got a little screwy in your registry.