Why won't my compact flash card boot?

I have built up an windows xp embedded image and copied it to a compact flash card to run in a thin client pc. I formatted the card in xp as FAT32 and copied the image files across. However, it won't boot. I just keep getting disk errors. The compact flash sets itself as the secondary slave. I have run bootprep on the compact flash card from a floppy but this had no effect. I see people mentioning about the flash card needing to be fixed not removeable. Is this the problem?

Many thanks in advance.