BradleyT - 5:01 pm on Apr 30, 2010 (gmt 0)
but this time I changed to it so you see the old name in the address bar on Firefox
Woah, that's even worse! You do not want 2 URLs to show the same content. You do not want example.com and example.ca to load the same page! You want one of them to redirect to the other one.
In my opinion the redirect has nothing at all to do with your rankings drop. If it really was the cause then you should point that domain at your competitors!