Now the funny thing: I can boot my notebook computer successfully from the CF when it is in the card reader. But when I put it into the CF => IDE converter of my zeroshell box it says “Disk boot failure insert system disk and press enter”. Funnily enough, I can successfully boot from another CF card with another linux installation so all the bios settings seem to be correct. The CF disk also is recognized by the bios so i wonder why i can boot from it via USB but not via IDE. Any suggestions?
Solved: For some reason the CF cannot be booted from when connected to a UDMA Controller (HPT376). While I have no problems booting HDDs or other CF Images from that controller, Zeroshell fails, not even Grub shows up. As soon as I connected it to a regular IDE port it worked – but not after trying to boot from the UDMA controller because that obviously destroyed the boot sector, I had to dd the image again to the CF before booting from IDE.
That just applies to older mainboards that have separate UDMA-IDE controllers.