About an hour ago, XNotifier showed an unusually large number of unread emails in one of my email accounts. I clicked on the context menu item to take me to that account, but I was taken to an entirely different person's account. I was logged in, so I could actually see his emails. I don't know this person, never corresponded with him, to the best of my knowledge.
Updated browser
While gathering info for this report, I found that there is a new version of Firefox available. I updated to FF 34.0, but the problem is still occurring.
I have disabled XNotifier until a resolution is found.
Details...
One item that might help the developer is to know with which email provider you are experiencing this unusual behavior.