[H] Odd hard drive issue

[Thane Sherrington]

I have a WD SATA drive that passes all SMART tests, and appears to 
work fine, but when I cold boot, it doesn't detect (and I get a boot 
disk error).  If I immediately warm boot, it detects and boots up 
fine.  It does this in two PCs, so it's the drive, not the machine.

Any ideas?
T