INACCESSIBLE_BOOT_DEVICE

Can anyone help with this problem. I have several computers periodically blue-screening with STOP error 7B INACCESSIBLE_BOOT_DEVICE the next code differs from machine to machine but the third section always shows 0xC0000032.

Try as I might I have been unable to find a mention of this in the Microsoft Knowledge Base and am unable to resolve the problem, which means I am constantly having to re-image them.

All machines are identical build Celeron 1.2GHz, 128mb RAM, Intel 815EG Mainboard running WIndows 2000 Pro.

Any ideas.