screen corruption when switching to TTYs

[Konstantin Svist]

I have a laptop with nvidia card (8600M GT (rev a1)) where I just
installed F11 x86_64.
I've added vga=0x369 to /boot/grub/grub.conf (that's 1860x1050, native
resolution).
The system boots up without incidents.

While in X, I try to switch to TTYs (Ctrl+Alt+F2, for instance). Instead
of a tty, I see a corrupted image of the desktop - there are diagonal
lines and everything is mangled beyond recognition, but the colors kind
of match the desktop content.
If I press Ctrl+Alt+F1, it goes back to the desktop without any visual
glitches.

Before I set the vga kernel param, switching worked perfectly. Of
course, the resolution was very low, so I don't want to go back to that
if possible.

Anyone have the same problem? What can I do about it?

Thanks