From http://support.microsoft.com/kb/225551, although that has a date in 2007.Note that if the volume existed before the disk was upgraded to dynamic, it can never be extended or spanned no matter which file system it uses. If you try to extend this type of volume, you receive the following error message:
The selected volume was originally created on a basic disk and cannot be extended. Only volumes originally created on dynamic disks can be extended.
To extend or span a volume that was created before the disk was upgraded to dynamic, the volume must be deleted and re-created on the dynamic disk.
A simple volume cannot be extended or spanned in this situation because any existing basic partitions retain their partition table entries in the master boot record (MBR) so that Windows 2000 can boot from and install to the dynamic volume. Setup allows only installations and upgrades to dynamic disks that currently include the system or boot volumes. Extending or spanning a simple volume that still has a partition entry would disable this ability.