The installation of RHEL4 update 5 hangs during installation process while trying to probe devices. To get out of this problem while installation use the following command line:

linux pci=nommconf all-generic-ide

or

linux pci=conf1 all-generic-ide

Once the installation is complete do not forget to modify grub.conf, else it wont boot up. Modify grub.conf file to pass “pci=nommconf” as additional parameter to kernel.
Example:

title Red Hat Enterprise Linux ES (2.6.9-55.ELsmp)
        root (hd0,0)
        kernel /boot/vmlinuz-2.6.9-55.ELsmp ro root=LABEL=/1 rhgb quiet pci=nommconf
        initrd /boot/initrd-2.6.9-55.ELsmp.img

We had to write a daemon in Java and opted for using common daemon from Apache. It worked fine on Ubuntu Linux. One day we shifted to Fedora Core 6 and then the daemon stopped working.
While debugging the issue with -debug option for jsvc which is used to start and stop the daemon we figured out that even after providing commons-daemon.jar in the -cp (classpath) option for jsvc, it was unable to find the daemon loader.
“23/01/2007 15:42:33 9252 jsvc.exec error: Cannot find daemon loader org/apache/commons/daemon/support/DaemonLoader”

So after debugging, we did the following: Checked that the owner is root for all files (jars) and then ran the daemon, it ran (WOW, man this is kind of unusual, we need to make jsvc better).