Find Hard Drive Location

sounds like harddisk0 is the primary bus of the motherboard and harddisk1 is the secondary
and d sounds much like windows world...so its the slave.
U have cable selection configured on the disks?
might be that if so, it aint workin as should. put master and slave, see if it helps.

Guess it depends on which drive you are booting from!  There are dozens of tools you can use to find out just exactly which drive letters are assigned to which drives - like SANDRA, Microscope, etc.

If 3 are on IDE, I take it the other 3 are on SCSI - right?  If you are booting from SCSI, just check your SCSI BIOS.  This should tell you the order.  Your HDD Manager should also be able to tell you more.  The device, \Device\Harddisk1\D indicates (as masa77 said) it is the second drive in your chain.  If booting from IDE, then it should be the slave drive on your primary controller - if booting from SCSI, check the IDs in the event you have done any manual drive letter allocations.

I have heard of this issue with UDMA133 drives on UDMA66 controllers..

The controller can't keep up with the burst mode of the drive and you get drive access errors.

If possible force the drive (via controller card software or bios settings) to run at the same DMA as the controller..

WHICH drive depends on where you're booting from..

Apply a "Volume Label" to all the drives..
It "names" the drives in "My Computer" with something other than a letter and that name doesn't change even if the assigned drive letter does.
Then simply look in My Computer and see which drive is missing.

PCBONEZ
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rindi has this one right.  It must be the power connectors.  Sure enough, I reconnected them, and the problem was solved.  I have a big enough power supply, but how can I get better connection though these cables?  Maybe gold plated connectors?

Maybe you can get High quality connectors, although I haven't seen any yet. Once SATA has replaced the old disks this problem should be gone, as the SATA connectors seem to be better to me.