Permissions problem

[NW]

I have been looking at the possibility of using my one printer for all
three computers at home, see other thread. Now I don't know if I have
done anything silly but .....

Yesterday I couldn't print anything. Research tracked down the problem
to the permissions on dev/lp0. They were  rw-rw---- with user = root and
group = lp. So others had no permissions.

I used chmod (with sudo) to change the permissions to rw-rw-rw- and I
was then able to print. Fine.

Today same problem. The permissions had reverted to rw-rw----. I have
changed them again. Now I don't want to have to keep running chmod every
session, that is just silly and anyway it has only just started to happen.

Can anyone help here please? For a start I don't understand why the new
set of permissions changed back. Shouldn't my change remain fixed?

If it is relevant I am running kubuntu Hardy on this computer.

Thanks

Neil