wix and iis - unable to update metabase error

I have a wix project that installs a web site (MVC2) to an existing web site the user selects. This works fine on my machine (of course) but the client is getting the following error on there test vm's:

Action 16:08:03: ConfigureIIsExec. 
Action 16:08:03: WriteMetabaseChanges. Installing Metabase Keys and Values
WriteMetabaseChanges:  Error 0x80070003: failed to create metabase key: /W3SVC/1/Root//
Error 26103. Failed to create metabase key.  (-2147024893   /W3SVC/1/Root//      )
MSI (s) (5C!64) [16:08:06:747]: Product: Blah Blah Web Site -- Error 26103. Failed to create metabase key.  (-2147024893   /W3SVC/1/Root//      )

Anyone got any ideas? They tried with IIS Metabase editing on and off and are running the installer as admin.

Your clue is here:

7]: Product: Blah Blah Web Site -- Error 26103. Failed to create metabase key.  (-2147024893   /W3SVC/1/Root//      )

Error -2147024893 means ERROR_PATH_NOT_FOUND.