Setting up linux-image-2.6.18-4-686 (2.6.18.dfsg.1-12etch1) ...

 Hmm. The package shipped with a symbolic link /lib/modules/2.6.18-4-686/source
 However, I can not read the target: No such file or directory
 Therefore, I am deleting /lib/modules/2.6.18-4-686/source

Running depmod.