ThinkPad 760XL - Dock I CDROM *sometimes* not detected by Warp 4/FixPak 15

[Edward Mendelson]

Can anyone help with a completely baffling problem with OS/2 Warp 4/FixPak
15, running on a ThinkPad 760XL with a 20X IDE CD-ROM installed in the Dock
I?

More or less at random, the second IDE controller isn't recognized at
bootup, and the CD-ROM isn't displayed in the Drives window. This sometimes
seems to fix itself after a reboot or powerdown/restart, but sometimes it
doesn't.

The problem wasn't fixed by installing the latest IDE and Removable Media
fix from IBM's Device Driver Download site (the download file is
IDEDASD.EXE, and the Readme file is dated 11/25/03; the IBM1S506.ADD file is
dated 10/13/03).

I have this line in CONFIG.SYS:

BASEDEV=IBM1S506.ADD /V

and the message "Adapter not recognized" (or something very similar) appears
for Controller 1 during bootup when the problem occurs.

As specified in the readme with the fixed driver, I've changed the /V
parameter to /W:1 so that it pauses during bootup; when the failure occurs,
Controller:0 is OK (that's the hard disk), but this line appears also:

Controller:1 Port:0170 IRQ:000F Status:Adapter not detected.

Yes, I have enabled the IDE device in the doc in the configuration program.
I've also opened a DOS window and typed PS2 ? IDE2 and got the result:
"Current State: Enable" for the second IDE device, and IRQ 15 is listed as
"Currently Assigned" to "Second IDE" when I type PS2 ? IDE.

I don't boot to other OSes between OS/2 boots.

Can anyone suggest a solution to this? Many thanks in advance.

Edward Mendelson