So it's "Blinder" :-) Which kernel version are you using? "$ uname -r" to know that.
I bet you are using the default 3.2; try installing linux-generic-lts-belenos , which is 3.5... If that doesn't help, try a newer Linux-libre kernel at http://jxself.org/linux-libre or https://launchpad.net/~linux-libre .
Pseudo-P.S.: when I installed linux-generic-lts-belenos, some Xorg drivers didn't come along; in order to install xserver-xorg-lts-quantal I needed to remove the trisquel package and the old Xorg ones, so I decided to give up, since VirtualBox dkms module is not compiling for 3.5 at all.
