User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1) Gecko/20061010 Firefox/2.0 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1) Gecko/20061010 Firefox/2.0 I have a page that includes the prototype.js (1.4.0) library. If I go to the page directly, everything is fine. If I open it through window.open, I always get an error on load. When I reload (F5/CTRL+R) it works properly. Reproducible: Always Steps to Reproduce: 1. Open the attached test case through a popup, like: javascript:alert(window.open('test.html')); 2. Note the error from Prototype's insertBefore. 3. Reload the window, note that it works correctly. Actual Results: Error on initial load only. Expected Results: No error.

You will need a copy of prototype.js 1.4.0 to go with this.

Aaaand, of course I forgot the cardinal rule: try disabling your extensions first. AdBlock was the problem, and once it was completely disabled (not merely "off") everything was fine. I will notify the maker and I offer my apologies.

I can confirm this issue, it seems to be a duplicate of bug 355161.

I spoke too quickly. The extension causes this to happen every time. Without it, this still occurs intermittently. Same behavior in a clean installation of FF2 on a clean machine with no extensions installed. I'm reopening because I don't know enough to tell if it should still be considered a dupe of 355161.

Bug 355161 has been fixed. Please download the latest Firefox 2.0 nightly from http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla1.8/ - if your issue is fixed there then this is probably the same problem.

I tested this again and it is indeed fixed in the 2006111503 Firefox 2.0 nightly. Resolving as a duplicate of bug 355161. *** This bug has been marked as a duplicate of 355161 ***