Alexander
To change the layer's properties, I think I don't need to open the ArcMap (at least, I'm not dealing with this option). So, the ActiveView is not necessary. Even way, I called Activate() for testing, and it makes no difference.
I've found a code that updates the information without connecting. I don't have it here right now, sorry, but it's something like "pWorkspaceName.ConnectionPropperties = pPropSet" after setting the pPropSet properly. It runs fine, but the information inside the layer did not change. Aldo, that .Save(true,false) is crashing the application. I couldn't understand how to set the parameters here.
Thanks for your time
Rodrigo Salvador