I think you already posted the answer. Just with the wrong focus:

To make sure: please add the precise error message to your post. You can do this using the edit function.
As to the actual problem: Please read this post Converting dynamic to basic disk. Note that this is something which I did not test myself and my own preferred way of recovering would be to wipe the disk (with diskpart clean - loosing all data) and to recover from backups (ghost images, wim files, clean re-install... pick your flavour).
Alternative solutions: (Partially from the post linked above):
- Manually edit the partition table changing partition types from 42 to 07. (Useful tool for this. This is described in details on this website.
- Or do the same using
diskprop.exe. as described on http://support2.microsoft.com/kb/913964
- Wipe the disk clean (diskpart, select disk 0, clean, create partition primary. Reinstall. Recover data from backup).
- Try testdisk
- Try a partition manager like this one
But whatever you do. First make a full disk backup.