Sometime by mistakes all file permissions get changed and you need to restore file permission. For example a shell script or some sort of corruption could change the permissions for packages (installed files), it may be necessary to reset them.
For example a long time ago my shell script run chmod and chown commands on /usr and changed the permission. Luckily rpm command can reset package permission. Sun Solaris pkg command and IBM can also reset permissions. Please note that this troubleshooting tip is about resetting the permission of the installed package files and not about end users files stored in /home directory.