Hi malberts,
First, to answer your question: I've got an NVIDIA Geforce 8300 GS video
card installed (came with the machine). I didn't try your suggested
solution, because "FRAMEBUFFER-y" was already in
/etc/initramfs-tools/conf.d/splash
Although the corrupt screen used to be displayed for at least a few seconds
during boot, it now only flashes for a moment before the boot screen is
cleared, hence there is not enough time to try the CTRL-ALT-F6 and F7 test.
I'm not sure when this change happened: Either when I installed 64-bit
Trisquel over 32-bit Trisquel, or when I changed the GRUB splash screen by
replacing trisquel-grub.png with one of Khany's artwork pngs and doing an
update-grub. The new splash actually displays correctly for a while before
momentarily appearing corrupt.
If needed, I can put the old one back in place, and/or take the FRAMEBUFFER=y
line out of /etc/initramfs-tools/conf.d/splash
Also, for the record, the vt.handoff=7 parameter is still removed from
/etc/grub.d/10_linux, it's possible that *did* make a difference. I'll try
putting that back in as well and see what happens.