Enumallwebs should list the sites that are orphaned too, so it is weird it fails!
Did you prepare for your upgrade properly by doing PreUpgradeCheck, and resolve all issues?
Did you do enumallwebs on the site before upgrading? Orphans should be deleted before attempting an upgrade rather than after...
Make sure you read up on the new tools for preparing for upgrade before doing the actual upgrade. A good source is Joels article series here or my own upgrade white paper here that Joel also have included in his book on upgrade.
Normally you would get an output like this:
<Sites Count="2">
<Site Id="e2a114b8-80c9-41f6-87bf-3feddf2ad9b6" OwnerLogin="Domain\username" InSiteMap="False">
<Webs Count="1">
<Web Id="064d8e7b-b349-4693-bd67-dcefed3bf466" Url="/sites/site_name" LanguageId="1033" TemplateName="STS#0" TemplateId="1" />
</Webs>
</Site>
<Site Id="f440114b8-79d9-32f6-87bf-4geddf2ad9b6" OwnerLogin="Domain\username" InSiteMap="True" HostHeader="www.contoso.com">
<Webs Count="1">
<Web Id="12348e7b-c456-4693-bd67-efdegd3bf466" Url="/" LanguageId="1033" TemplateName="STS#0" TemplateId="1" />
</Webs>
</Site>
</Sites>
Where the elements that has attribute InSiteMap="false" are the sites that are orphaned.
you could try (after doing backup etc) to delete the site using stsadm -o deletesite -siteid 2371cdd6-5ec8-46cd-ab34-4a5be24d6a70 -force
In general in-place upgrades are not reccomended due to the many ways it can go wrong. Read Joels article on the subject here.