It sounds like a problem with either your memory card or the files.
Some things to keep in mind:
1. While it normaly shouldn\'t be a problem, having extra files on the card \'can\' sometimes cause a problem, so if there\'s extra junk on the card, try removing it.
2. You can only flash using a CF card. Flashing from SD is not possible.
3. The card must be formated Fat16, NOT 32, not ext2, not ext3, not ntfs, not anything else, only Fat16 (also called vfat by some linux distros)
4. When flashing with an initrd.bin and zImage, you usualy need to rename them. THey almost always have a bunch of extra version information in the filename that needs to be removed. the names need to be initrd.bin and zImage EXACTLY, notice there is NO file extension on the zImage file.
5. You should always flash with the power plugged in.