Question about Outlook Express

Sending an email in Outlook.com causes my browser, Firefox, to crash. When I hit the send button on an email, Outlook plays the animation that shrinks the email down and sends it off into the ether, and then at the end of the animation the browser closes and pops up Mozilla's crash reporting dialog box.

This is a new development that I only noticed today. Prior to today there were no issues. I have not installed any new software.

Interestingly, the browser will not crash in certain instances depending on the size of the browser window. Specifically, if I resize the browser window small enough so that Outlook shows the name of the email recipient above the body of the mail instead of to the left of the body, then the browser does not crash.

I am using the most recent version of Firefox. I have deleted the browser's cache. I have disabled all browser extensions and plugins. These efforts did not change the crashing behavior.

Specs:
Browser: Firefox 22.0
OS: Windows 7 Professional, Service Pack 1, 64-bit