failure to start kernel k8-smp

[Francesco Pietra <frapietra@alice.it>]

#aptitude
shows

i  linux-image-2.6-amd64-generic
i  linux-image-2.6-amd64-k8-smp
i  linux-image-2.6.15-1-amd64-generic
i  linux-image-2.6.15-1-amd64-k8-smp

and no brpken packages are indicated.
I was use to start
i  linux-image-2.6.15-1-amd64-k8-smp
before the problem below.
______________


Booting Debian GNU Linux kernel 2.6.15-1-amd64-k8-smp  root (hd0,0)
Filesystem reiserfs, partition 0xfd
kernel /boot/vmlinuz-2.6.15-1-amd64-k8-smp root -/dev/md0 ro single

Error 13: invalid or unsupported executable found
Press any key...

Same error trying in recovery mode.


It starts with the only other kernel available:
2.6.15-1-amd64-generic (the one used for the installation)

? It is debian amd64 etch, raid1 two 264 dual opteron 8 GB ram.

thank you 
francesco pietra