Instead of running `make clean`, run `make mrproper`. THEN copy the last config file to the build directory.
cd /usr/src/linux<vers> make mrproper cp /boot/config-2.6.5-1 /usr/src/linux/.config make oldconfig make modules make modules_install /sbin/mkinitrd /boot/initrd-2.6.5-1.358custom.img 2.6.5-1.358custom make bzImage cp arch/x86_64/boot/bzImage /boot/vmlinuz-2.6.5-1.358custom
edit grub.conf adding the 'custom' kernel & initrd, then try to boot to it.
## note that 'custom' suffix must be the same as that defined in file Makefile. Also, the last two lines can be sub'd for `make; make install` (though some folks prefer the manual kernel copy)
The recommendation to use `make mrproper` comes from the /usr/src/linux<VERS>/README file. Conversely, many 'howto' websites dont even make mention of it. Goes to show you (and me :-)): RTRM (Read The REAL Manual)
Lesson learned.