She was Provost there from '93 to '99, which is a little more than teaching [1]. I think that while her willingness to go with the Bush administration's extremist positions (on torture and surveillance, especially) are a dark mark on her career, Dropbox is worth dropping for wholly different reasons (e.g. technical incompetence [2]) than who is on their board.

1. "As the chief academic and chief budgetary officer of the University, the Provost is responsible for administering the academic program, including both instruction and research, and for the coordination of the administrative and support functions of the University with its academic purposes." (https://provost.stanford.edu/)

2. http://www.eweek.com/c/a/Security/Dropbox-Accidentally-Turne...

I disagree. As a professor at Stanford, she's teaching the future rulers of the world how to rule. At Dropbox, she's showing up to board meetings and taking a salary.