Guest OSs With no ATAPI CD-ROM Support May Fail to Boot

Details: Some guest operating systems predating ATAPI CD-ROMs may exhibit long delays or entirely fail to boot in certain configurations. This is most likely to happen when an IDE/ATAPI CD-ROM exists alone on a primary or secondary IDE channel.

Affected operating systems are MS OS/2 1.21: fails to boot with an error message referencing COUNTRY.SYS and MS OS/2 1.3: long boot delays.
Workaround: Disable the emulated IDE/ATAPI CD-ROM. The guest OS can't use this device, anyway.