Think I replied to one of your earlier posts about this and recommended that you NOT set the Axe USB as default audio device. I did try doing that on Win7 x64 and it did swap to the audio card when the Axe was off, and back when I powered up the Axe. IOW - it worked for me.However, my problem now (on my Win 7 desktop) is not MIDI but audio. I do the driver install, which "seems" to go OK. I say that because when I check the sound devices, AXE II shows up and if I right click on it in Device Manager it says it is working properly. However, as soon as I set it as the default, anything referencing audio hangs. This includes the Audio Device dialog where you can click a speaker to test, Win media player, and of course the Axe. In fact one time I couldn't even open the Device Manager dialog. I kept getting error dialogs with hex characters...very strange.
I still think the drivers not installing correctly is the root cause of your issue.