Windows PE Bootable CD

Hello,

I have followed Microsoft guide on how to Create a Bootable Windows PE RAM Disk on CD-ROM and created the boot CD. But when i boot to it, I get the DOS screen with things like ‘USB support successfully initialized’, ‘ No FAT32 volumes found, exiting’; ‘Caldera DR-DOS 7.03’, but then it presents me with the A:\> dos prompt and my keyboard just doesn’t work anymore. Could it be becase I am using USB keyboard?
I have tried a couple of machines (Dell Optiplex GX620 andoptiplex 745) .
Please help.