Force ubuntu to keep old package installed

I use vnc to login as another user on my computer from another computer. I can even login as another user from anywhere that has the internet. My vnc program was uptodate and it doesn't work unless I use the last version of vnc4server. So I open synaptic package manager and find vnc4server. The version I use that works is 4.1.1+xorg1.0.2-0ubuntu1. This version is for Edgy but a new update came called edgy security. When I install this version I can't login to one of my users from another computer while I am already logged on in the physical computer. So I clicked on vnc4server in synaptic package manager and clicked on package tab and force version then I chose the older release. Now the problem is when I turn on my computer the auto updater keeps bugging me so I found a work-around.