stsadm can inadvertently delete a root site collection if erroneous URL path used
No content databases are available for this operation. Create a content database , and then try the operation again. To create a content database, click "Content databases" on the Application Management page, select the Web application to use, and then click "Add a content database".
Going to the now dead root site you get:
404 FILE NOT FOUND
Microsoft Office SharePoint Server 2007 unsupported scenarios using stsadm -o export /import of subsites
Microsoft Office SharePoint Server 2007 does not support stsadm -o import of subsites based on the publishing feature as a root site collection as this subsite would have orphaned information stored in the root site the subsite was exported from.