nightmare with ASP, IIS6 & VC6 PSDK

I have been having a nightmare with ASP/ASP.NET & IIS6.

We use Msxml2.DOMDocument.4.0 object to create a XML object in ASP. The
Msxml2.DOMDocument.4.0 is from the Windows Platform SDK Feb 2003 (the last
version compatible with VC6). Then we use
TranslateXSLT(XMLDocument.transformNode) passing in a xsl file path. Our
pages work perfectly fine under IIS5 & IIS6 onsite. However strange things
happening at our clients IIS6:

- transformation just displays the xml nodes instead of the html code.

Probably it's nothing to do with IIS6. Maybe it's Msxml2.DOMDocument.4.0
from Platform SDK Feb 2003?

Anyone has any ideas?