Can't install older version of comcat.dll

I'm getting the ActiveX error on my local PC where it tells me that this page provides potentially unsafe information. The control is signed, and used to work, but now no longer works.

After doing some research, I discovered that comcat.dll v5 doesn't want to work correctly with Windows 2000/NT so one needs to remove it and install comcat v4.

I follow the instructions on the Microsoft website, but as soon as I try to rename comcat.dll to comcat.bak, it works but then a new copy of comcat.dll is created in my winnt/system32 folder. This prevents me from installing the older version of comcat..

Any ideas?

Greg