'Thanks for your message and reporting this issue. It only affects Google Apps for your Domain (incl. They're aware of the issue are will have a fix by November. UDPATE: While I was writing this, I got a response from Google on the issue.

('Quit and Save' works every time as long as both tabs are open when the user quits, and the user logs into our system on the Gmail tab FIRST.cannot log into our main system tab first, or it won't work. If, however, the user quits Firefox normally and chooses 'Quit', it's back to not working. What was really happening was if both the parent and child (Gmail) tab were open when Firefox restarted, everything worked perfectly once FF restarted and they logged in directly on the Gmail tab (it would redirect after logging in to our login screen.) This happens because when clicking 'restart' after enabling or disabling an add-on, FF saves the session. On a side note, the reason it was sometimes working after installing or uninstalling Google Toolbar had nothing to do with Google was 100% coincidence. That page sets parent.opener to null then redirects to Gmail. We changed the link in our main application to point to another page in our application instead of directly to Gmail.

We discovered this by accident: if you CLOSE the parent tab, it then starts working correctly. That tab is now a child of the first tab.When trying to print or open a message in a new window, Gmail tries to go back to the parent tab for something and gets permission denied.so nothing happens. We're using Google Apps for Education (same as the Domain version.) Our users log in to our own system, then click the 'My Email' link to open Gmail in a new tab. The fact that some users have never even had the Toolbar tells me it has to be something else, but no idea what it could be.

The process of either installing/uninstalling/and-or re-installing the Toolbar works for a short period, then it's back to broken. But then I ran across users that had *never* had Google Toolbar installed, and they were having the same problem. At first I was sure it was a problem with Google Toolbar because the first couple users all had it installed, and after uninstalling everything seemed fine. Re-installing Google Toolbar worked, again for a day or two, then it stopped working again. Uninstalling Google Toolbar worked.they would print again.for a day or two, then it stopped working again. * Some users had FF 3.5.x with or without Google Toolbar installed. If I uninstalled Google Toolbar then re-installed it, they could print again.for about a day, then it stopped working again. * Some users had FF 3.0.x with or without Google Toolbar installed.

When you click Print or Print All, nothing happens. Starting last week, our entire office has been having trouble printing emails in Gmail.

Gmail not working in firefox