Run kudzu again to redetect your hardware.
Have you ever set up a modem in your system?
If so, try deleting the setup from the Sytem-Networking-Hardware box, or by removing /etc/sysconfig/network-scripts/ifcfg-ppp0
Also, when a kernel is compiled, it creates a list of the modules it expects to find and complains when they are not there.
Do depmod -a and see which modules are still missing.
They should be in the /lib/modules directory under your kernel version number.
If there are some still missing, you will need the kernel-source package to rebuild them.