I've tried changing the MAC with macchanger and just by typing in the command line
sudo ifconfig eth1 down
sudo ifconfig eth1 hw ether xx:xx:xx:xx:xx:xx
sudo ifconfig eth1 up
After I change the MAC I run ifconfig and it shows the new address correctly, but when I try to connect to a network, it gets hung and never connects.
If I change my MAC back to its original value then it works just fine.