iexplore.exe

Weather you have an infection causing it or not may be in question here.
Iexplore.exe is the executable file for the program Internet Explorer.
If it's using an extensive amount, you may want to look into the "Add On's" running in Explorer instead of Explorer itself.

How are you determining that it is iexplore.exe using this amount of processor?
and how much processor is it using?

Also, do you know how to do an Explorer reset?
It can fix these types of problems.