Blowing the BRE in King George, Pro Bass, TWICE, after nailing it in Practice mode.
I think the Mustang is oversensitive to strums. That, combined with the looseness, renders it as functional as the Power Glove.
And now I would like to add another epic fail: Having to RAGE QUIT by yanking the power cord from my 360, to prevent the game from recording my 4-star performance of I Love Rock and Roll. Thankfully, the save file was not harmed.