Running: Linux ips-svf-1 3.0.0-22-server #36-Ubuntu SMP Tue Jun 12 17:56:20 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

I'm trying to free space in /boot with apt-get -y purge, but every time I run the command I get an error about unmet dependencies:

sudo apt-get -y purge linux-headers-3.0.0-12
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 linux-headers-3.0.0-12-server : Depends: linux-headers-3.0.0-12 but it is not going to be installed
 linux-image-server : Depends: linux-image-3.0.0-26-server but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

However, I can't run apt-get -f install since /boot is full.

I also tried running dpkg --purge and dpkg --remove manually, but both give the same unmet dependency error.

Any suggestions on how I can successfully free space in /boot? Is there anything I can delete with rm?