In the legacy web-based systems (ASP Classic) it was common to use COM object as part of the website implementation. If you need to maintain such a system ( I assume no one develop a new system in ASP Classic) then you will need know how to debug the COM object.
If the COM object is a ActiveX developed using VB6 then you can follow these steps to debug its code:
1. Run the ActiveX VBP project in the Visual Studio (using F5) on the same machine that the website is running.
2. Put a breakpoint on one line of VB code.
3. This step is bases on XP operating system. Go to IIS Manager and get the property of the website. On the [Directory Security] click on the Edit [Anonymous access and authentication control] button. Untick the Anonymous Access.
4. Restart the IIS. You can type “iisreset” in the command line or use IIS manager.
5. Run your website and navigate to a page which executes the code you want to debug. Once the code get to the breakpoint it will stop and the related code in the Active X will be highlighted.
This process is described in “How To Debug Visual Basic COM Components That Are Used Within Active Server Pages” Microsoft support article.