How to kill Google Chrome (from behind a corporate firewall)

This is quite annoying. Most annoying is the fact that I do this every single morning without remembering the issue.

1. Start up Chrome.
2. Before the proxy sign-in window has a chance to come up, open a new tab.

Stop. You've done enough. From here, you can't seem to do anything, no keypress or mouse-click works, and you have to kill the process and start again. I imagine if you wait long enough, something will time-out, but you know...