I had same issue with 8.04. I removed through synaptic my custom kernel 2.6.25. And later during an update i noticed this:
Processing triggers for libc6 ...
ldconfig deferred processing now taking place
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-2.6.25.3-custom
Cannot find /lib/modules/2.6.25.3-custom
update-initramfs: failed for /boot/initrd.img-2.6.25.3-custom
dpkg: subprocess post-installation script returned error exit status 1
Managed to solve the issue by removing stale configuration files in /var/lib/initramfs-tools
I had same issue with 8.04. I removed through synaptic my custom kernel 2.6.25. And later during an update i noticed this:
Processing triggers for libc6 ... img-2.6. 25.3-custom 2.6.25. 3-custom img-2.6. 25.3-custom
ldconfig deferred processing now taking place
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.
Cannot find /lib/modules/
update-initramfs: failed for /boot/initrd.
dpkg: subprocess post-installation script returned error exit status 1
Managed to solve the issue by removing stale configuration files in /var/lib/ initramfs- tools