The single best source of information, especially with respect to bugs or
problems with the Red Hat Linux distribution are the errata pages,available at
http://www.redhat.com/support/docs/errata.html. Be sure to review both the general errata as well as the platform-specific errata specific to your version of Red Hat Linux. (See also Section E.4 for other ways to access the errata).
It may seem strange that we list this as the very first item, but the errata pages are perhaps the best resource for fixing 90% of the common problems with Red Hat Linux. In addition, security holes for which a solution exists are generally on the errata page 24 hours after Red Hat has been notified.
You should always check there first.