Mac mini mid 2010 hard disk keeps ejecting itself

Question

My mac mini is set up with two sata disks installed, one is a 128 ssd and the other a 1tb hdd.  Since installing mountain lion, the hdd keeps ejecting itself, and i get a message saying - this hard disk was not properly ejected. then i wont find the disk in finder, or disk utility!.  I then have to remove the hdd from the mac mini and plug it into a usb caddy, which finds it no problem, and then when i put it back in the mac mini, it works again!! so the disk is not faulty i dont think.  It then works for a period as random as a few hours, to a few weeks and then i will randomly get the "this disk was not ejected properly" message and it has again dissapeared.  I use the mac mini as a media centre and it isnt really being pushed hard when the failure happens.
Anyone have any ideas as to whats wrong?

Answer 1

Hello, Sorry for the late reply.
When i open console after the ejection i get the message:
01/11/2012 22:32:42.000 kernel[0]: Failed to issue COM RESET successfully after 3 attempts. Failing...
01/11/2012 22:32:42.000 kernel[0]: disk1s2: no such device.
Hope this gives a clue, i'm tearing my hair out over it.  there is absolutely nothing wrong with the disk itself.
If i do a full shutdown and restart, it finds the disk again no problems, but if i simply choose to restart from the menu, it does not find the disk again.
Thanks for any help you can give on this.  I have only been experiencing this issue since i upgraded to mountain lion.
Drive information:
SAMSUNG HN-M101MBB:
  Capacity:          1 TB (1,000,204,886,016 bytes)
  Model:          SAMSUNG HN-M101MBB                     
  Revision:          2AR10001
  Serial Number:          S2R8J90B815515     
  Native Command Queuing:          Yes
  Queue Depth:          32
  Removable Media:          No
  Detachable Drive:          No
  BSD Name:          disk1
  Rotational Rate:          5400
  Medium Type:          Rotational
  Bay Name:          Lower
  Partition Map Type:          GPT (GUID Partition Table)
  S.M.A.R.T. status:          Verified
  Volumes:
disk1s1:
  Capacity:          209.7 MB (209,715,200 bytes)
  BSD Name:          disk1s1
  Content:          EFI
living room:
  Capacity:          999.86 GB (999,860,912,128 bytes)
  Available:          648.66 GB (648,662,093,824 bytes)
  Writable:          Yes
  File System:          Journaled HFS+
  BSD Name:          disk1s2
  Mount Point:          /Volumes/living room
  Content:          Apple_HFS
  Volume UUID:          D6125397-BAE7-3496-9B9C-6534EEE0B660