I don't have the problem, but out of curiosity:
I think either vmlinuz is really missing, or GRUB links to it the wrong way.
vmlinuz is supposed to be in the /boot folder as far as I know
(https://superuser.com/questions/62575/where-is-vmlinux-on-my-ubuntu-installation),
so that would be the first thing I'd check.
From there, either it's a problem with the Trisquel install, or GRUB needs to
be updated I guess.
Either way, you'd neet to chroot (a.k.a. "mount the installed partition").
If you have no /boot, maybe it's on its own partition:
https://bbs.archlinux.org/viewtopic.php?id=132806
