PC will not recognise 3 drives but recognises 2

Can anyone help with the following ?

I have just purchased a third My Book Essential 2TB external drive as part of my backup strategy for a small office network. The system worked OK with just two drives, but I am now having problems in that the system will not recognise one of my three drives connected to the same USB hub.

They are all connected to the same PC via a 4-port USB 2.0 hub and the PC operates under Windows 7. No other USB devices are connected, but I can only see two of the drives in My Computer.  However, if I check the USB section under Device Manager, I see that all three drives are connected and it says they are working properly.

  1. It cannot be a faulty drive as it will recognise any combination of two drives (ie 1 & 2, 2 & 3, or 1 & 3), but will not recognise all three together.

  2. It cannot be a faulty USB as I’ve also tried connecting them to an IOMEGA multiport USB server accessed across the network.  Again, the same problem - it will only recognise 2 of 3 drives.

  3. When connected as network drives as described above, I have tried accessing them from another PC operating under Windows XP SP3.  Again the same problem - only 2 of 3 drives are visible in My Computer.

Any ideas ?

many thanks,

Keith (soberhill)

I’ve now resolved my problem.  It was caused by a drive signature collision.