Ok, there are 3 location you have to check

/etc/multiboot.d
/lib/module
/boot

In /etc/multiboot, you should find your *.item file which content should be like this (copied from mine):

ITEM_NAME="Maemo kernel-power 2.6.28.10-power48"
ITEM_KERNEL="2.6.28.10-power48"
ITEM_MODULES="ext3"

In /lib/modules, you should find a folder containing a lot of .ko files (the kernel modules) and this folder should be named 2.6.28.10-power48

And finally, in /boot you should find the bootimg named zImage-2.6.28.10-power48

If ouy miss any of those files, you will have to reinstall kernel packages.