SBS2003 Company web broken, but http://companyweb/default.aspx works

I was at a customers today where the COMPANY web entry into IE actually
downloads a web.config file, but it's really a packed binary and not a
web.config file.

Opening http://companyweb/default.aspx works fine, as does

I have checked all of the IIS Manager settings for the COMPANY web site,
all tabs and boxes match another working SBS server. the default.aspx is
in the documents list.

I have used the BPA and it passes

I have restarted the server, but HTTP://COMPANYWEB fails and wants to
download a file, but http://companyweb/default.aspx works fine.

Any ideas?

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