error when running appcmd list site

 Hi,

Does anyone know why when i run 'appcmd list sites'  it displays a couple of hundred sites and then displays the following :

 ERROR ( hresult:8007007a, message:Failed to generate item output.
The data area passed to a system call is too small.
 )

   The command never completes and stops at the same spot everytime.. i have checked the config and there doesnt appear to be any odd characters etc.

Thanks,

Chris