On Windows XP, I just upgraded to Adobe Reader 9.0.0, and now I get two copies of a message saying that iertutil.dll is missing every time I launch Reader. I've tried re-installing, didn't help.
Thinking that "iertutil" might mean "Internet Explorer Run-time Utilities", I'll provide the additional info that I still have IE 6 on this machine (I never use it and would rather not upgrade if I can avoid it).
I think you are right that it belongs to Internet Explorer. Internet
Explorer is a system requirement, but IE6 is listed as OK
(http://www.adobe.com/products/reader/systemreqs/#90win). It may be
worth just starting IE6 to make sure it still works OK, to see whether
it needs to be repaired.
Some reading on the internet suggests that this problem comes from
bits of IE7 being on the system.