Reply To: It says here that Ubuntu updates every six months
To answer your question more directly, AFAIK, no, specific parts of your system do not stop working, everything in a particular Ubuntu release is either supported or has reached support end-of-life. Also, it doesn’t follow that if you stop updating, things fail to work. It’s not like some DRM schemes where your license and therefore function only lasts for a given period. You could be running Ubuntu 8.10, it’s just that you will not have any updates for over six years, and depending on what you’re running, it may work just fine, or you may be subject to vulnerabilities. In that sense, it’s kind of like running Windows XP; it works fine most of the time, but it’s best not to connect it directly to the Internet, and to be extremely careful when accessing anything not on your computer. It’s even moderately unsafe to put Ubuntu 8.04/Windows XP on your LAN because if one of your other systems is compromised, it’s possible that could be used as a springboard to attack your out-of-date system (so the BEST suggestion is not to network it at all).