"cg 0: bad magic number"

[Niels S. Eliasen]

I have stumbled upon this rather annoying error....
Thought it was just this was one specific disk.. but have tried with  
several and all get the same error...

did the partitioning using either Disk Utility or pdisk on MacOSX  
10.5, and subsequently tried to "newfs /dev/da0s3"

example:

munin,root,~/ > newfs /dev/da0s3
/dev/da0s3: 73728.0MB (150994944 sectors) block size 16384, fragment  
size 2048
         using 402 cylinder groups of 183.72MB, 11758 blks, 23552  
inodes.



super-block backups (for fsck -b #) at:
  160, 376416, 752672, 1128928, 1505184, 1881440, 2257696, 2633952,  
3010208,

etc etc etc

  146740000, 147116256, 147492512, 147868768, 148245024, 148621280,  
148997536,
  149373792, 149750048, 150126304, 150502560, 150878816
cg 0: bad magic number

and obviously the "newfs" do not complete succesfully ....

any ideas ?