Yeah, if it's an issue in a nightly, it's likely related to a bug to a specific version. At the least, you need to try more nightlies. If you see an issue in a nightly that isn't in a stable release, you should report it to Mozilla.
Apparently it's a javascript issue. I too have had this issue on both Nightly and Aurora for quite some time now. I could test Beta if no one else wants to.