China DOS Union

When using IE5 to browse many forums and communities, as soon as I press "Back," the system gives this prompt: "The ActiveX controls on this page might be unsafe. Your current security settings prohibit running unsafe controls on this page. As a result, this page may not display correctly." But after I click OK, the page below still displays completely normally.
On some sites, even pressing Refresh makes this prompt pop up.

Before installing SP4, all of this was normal. My IE options are all the default ones and have not been changed, and there is no virus infection either.

I made a special trip to the Microsoft website to look this up. It said it was related to comcat.dll, but I followed its method and re-registered, unregistered, and replaced that file with an older version, and none of it worked.

Does any expert know the exact solution?

Please don't tell me to reinstall.

Could it be a security settings problem? Because I have this problem too, I'm just too lazy to look into it, and I'm still on SP3 now.