Created attachment 742756 [details] "0" showing up at webpages I've seen this happening on at least 3 websites since a few days ago, including our yammer instance (see a red bar with "00" in the bottom of the page). Here are three URLs where I can see it:  http://www.cvc.com.br/index.aspx - one "0" on top right  http://globoesporte.globo.com/temporeal/futebol/27-04-2013/sp/mogi-mirim-botafogo-sp/ - many zeroes on middle of page  http://www.yammer.com/ after logging in to our network (see attached screenshot for all these urls) I used mozregression with a mix of URL 1 and 2 and that led to the following: Last good nightly: 2013-04-22 First bad nightly: 2013-04-23 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=50d25e083421&tochange=acf388eaf9e9 However, I'm not 100% confident with that range. When it came down on the last test (it was for 2013-04-23 to decide between the 23rd and 24th), the test case seemed to differ between URL 1 and 2. (worked correctly for URL 1 but bug showed up for URL 2, so I marked 04-23 as bad). I tried then to only use URL 2 in a new bisect with a few days of range, but 2013-04-21 crashes everytime with URL 2 for me, so I didn't continue.