Bugs are a part and parcel of software development. They are there for us to remind that we need to improve the software all the time. Theoretically, critical and security bugs should be taken care of as soon as possible. Other bugs e.g. normal and feature requests are resolved as the developers get round finding time for them. But there are some bugs which live for a long long time. By long I mean really long! Check out the brief details of the top three (age wise) bugs for the Debian GNU/Linux system on this page. The oldest one is going to be 10 in a few days!
I wonder if there are bugs older than those!!