system
8
Unless a member of the avast team or someone more knowledgeable chips in that’s about all I can suggest - keep disabling things and see if you can track down the culprit.
(I take it you’ve already tried clearing IE cache?)
I would try uninstalling webrep from IE10 too. Shouldn’t logically be connected, but I do recall a plan for webrep to also interrogate malware info sources - and a scriptshield library may possibly be one of those sources? Don’t know if it was ever carried through though.
As a last resort you could try a complete uninstall/reinstall of avast - with no guarantee that anything will change though.