Installing with the ncurses installer from livecd-i686-installer-2006.0.iso, fdisk does not mark any partition bootable. With some BIOSes this causes the well known "Invalid System Disk" error from the BIOS. Manually adding the bootable flag fixed it. Harware PEAK630VL Industrial P3 Single Board Computer
We've gotten a similar bug before from a user, but it was decided that the installer would not do this, especially since the current code does not allow the user to select *which* partition has the bootable flag.
*** Bug 152702 has been marked as a duplicate of this bug. ***