Exporting WLM to Outlook 2000 PST

[Datanomics]

I exported my email from Windows Live Mail (version 2008 Build 12.0.1606) to an Outlook 2000 PST.

Every time I open one of those exported emails in Outlook 2000 I get the following prompt: "The custom form could not be opened Outlook will use an Outlook form instead. The object could not be found." I hit OK & the email then opens without a problem.

How do I disable this prompt so the message opens without that extra step?

Thanks!