My WD2500 doesn't seem to be dead, but I need help

My Dell laptop suddenly stopped booting from the WD 2500 BEVE drive.  When booted from a CD using Seatools for DOS the drive passes both the short test and the long test. SMART is clear, nothing seems to be amiss. 

With the WD2500 the laptop goes through post, and when it should read the drive it just stops.  No error message, the drive light doesn’t light, just a blinking cursor in the corner of the screen.

The laptop boots from it’s original drive. 

Unfortunately I have no way of further examining the drive.  I remember reading somewhere that the drive might have security settings that could disable it, or that power up in standby might have been accident which would prevent booting. But I haven’t been able to find anything I might do to fix it.   I don’t know.  I’m grasping at straws here.  Also I have an RMA from a couple of months ago for this unit that I have to renew if I can’t get it working…

Try running another test with data lifeguard diagnostics, you can also check if a windows installation disk recognizes the hard drive.