How the problem occurs (could be reproduced on one PC, see further down, all worked well on another machine):
I installed from Gutsy live CD on an existing partition. Told installer to format the drive with ext3 and set mount point to /. The installation finished but did not ask to reboot (as it did with the successful installation on another PC). I restarted manually and got the error:
grub stage 1.5 error 15
Some more info:
- I noticed that after installation but before booting, the system mounted most of my partitions to the same directory /target
- I have one SATA HD on controller plug 2 and an ATA CD-drive
- I have four Windows partitions (dev/sda1, sda5, sda6, sda7), swap (sda8), and fife linux partitions (sda9 - sda13)
I was able to repair grub manually and bottet my old feisty. I searched all the Linux partitions but nowhere were any files from Gutsy installed
so that was the reason for the grub error, the real error must be in the mount/partitioning
Correction:
I rechecked the partitions and found an installation of 7.10 in /dev/sda11 (which I chose for installation formatting and mount point /).
There is however no grub directory in /boot and only a .bak file of initrd.
I copied this to initrd.
To sum up:
The problem was that grub got installed but the partition /dev/sda11 did not contain the grub files