When will America begin to take Canada's trade issues seriously?

U.S. Secretary of State Condoleezza Rice recently warned Canada to stop threatening the end of the North American Free Trade Agreement because of the softwood lumber dispute.
Rice essentially said that this is just a trade dispute and shouldn't negatively impact the positive relationship the two countries share.
What positive relationship?
We thought any positive relationship went out the window every time our governing Liberals called George W. Bush a moron.
We were also pretty sure that good relationship between Canada and the U.S.A. suffered when we didn't join them in Iraq.
And now we hear that to keep our mouths shut and not take this trade dispute to the next level.
Despite Rice's strange warning to Canadians, we can't help but ask why would Canada not threaten to end NAFTA, considering the body that rules on disputes with this trade agreement has ruled unequivocally in Canada's favour and yet the American's have ignored that ruling.
What's the point of NAFTA if the body that is supposed to solve disputes becomes completely irrelevant?rnUnderstandably this is a slippery slope, but forestry is one of this country's most important industries. So why not make a stand. What other trade issue could have as large a negative impact on Canadians?rnPerhaps it is time to bring NAFTA to an end and then maybe the American's will begin to take Canada's trade issues seriously.