Does this happen every time you try to add a contact?

I've been unable to reproduce this with Safari so far.

It only happened a couple of times to me, but an associate had the same problem today on a different computer. I did notice that it happened to me initially only after attempting to add a contact that did not exist -- in other words, I tried adding a contact who was not an existing remember the milk member. That generated an error message, and the subsequent attempt crashed the browser.

Thanks for the additional info -- we've been able to reproduce this now, and it seems to be a bug affecting Safari only. We'll fix this soon.