You obviously didn't do "make modules" and "make modules_install." The order I suggest for a kernel is "make bzImage." Copy the bzImage and System.map to the place where the old ones are, backing up the old ones first. Then, do the "make modules" and "make modules_install." Another thing is that if you compile the same kernel more than once, remove the old modules before installing the new ones. For example, Slackware 9 ships with kernel 2.4.20. If you build a custom kernel from it and install its modules without removing the old ones, there will be lots and lots of errors about undefined symbols. Either remove or rename the directory for your modules before installing a new kernel. I always prefer to rename and keep it around until I'm sure the new kernel works right.
