Ok, but again, what does the WMI error have to do with this? Where or when does it show up?
Check to see if you have any browser add-ons as those are the most common culprit of this. Disable them, restart IE9, confirm they're still disabled, then save homepage, restart IE9, check if settings are saved.
Also, certain AV software like AVG is known to inadvertently cause this. See if disabling your AV engine temporarily will resolve the issue.