Web App Unable To Access Remote File Through IIS 5.0

I have this web app that works just fine when I run it on IIS 6.0, but when I run it on a different machine with IIS 5.0, it ends up having file access problems. Basically, my web app uses a COM object, and this COM object uses resources, such as files, and these files are located in remote machines. A sample code would be:

Code:
MyComObj com = new MyComObj();
com.UseDataFiles("machineBdata.dat");

Again, it works fine on my machine with IIS 6.0, but in my other machine with IIS 5.0, it gives me an error. To be more precise, it's the COM object that gives me an error; the com object tells me that it can't find the file. What's weird is that when the web app calls this line:

System.IO.File.Exist("machineBdata.dat");

It returns True, which means my web app has permission to read, but when it does it through my com object, it can't see it. Again, I dont' think it's the COM object that has the problem since it runs fine on IIS 6.0. In fact, I ran a windows form application (that uses the COM) on the machine with IIS 5.0, and it works fine.