There could be several reasons for this, most probably a security setting in your IE. You shoud try to google the error as there are several resources around like
My IE security settings are set as required. My code works fine on IE when used outside of QlikView Script.js.
I get this error only when I run it within Qlikview using extension object.
Also, have set system access on my macro settings. But the issue is only when I run from within QlikView.