Logical disk information containing “HarddiskVolume…” usually indicates an unformatted partition. Knowledge Base article (Q260834) describes the ‘HarddiskVolume’ label as a volume that has been mounted, but not assigned a drive letter. See http://support.microsoft.com/default.aspx?scid=kb;EN-US;q260834
There is another MS KB entry that specfically discusses “HarddiskDmVolumes” names. See
http://support.microsoft.com/?kbid=274311. This KB article explains that after you convert a hard disk from Basic to Dynamic, the volumes on that hard disk are not identified by their drive letter in System Monitor. Instead, volumes that are displayed in System Monitor in a form similar to the following:
You need to re-assign drive letters to dynamic disks after you convert them so that the drive letters are reported properly.