Same thing here on random sites on my Vista laptop and my Windows7 desktop. It's been persistent since upgrading to v15.0.

do you use the extension "draganddropupload" and switched to the private mode?

I found if I disabled the drag / drop / upload extension that the issue went away -- though I had to disable it twice and restart twice for whatever reasons ... but now the issue is gone.

I did have to position my cursor over the left-top Firefox menu and then click Enter a few times to get the extensions / add-ons area open ... and then I had to do similar maneuvering when the area was open.

Disabling Drag & Drop uploadd seemed to do it...on my 7 machine. Now for my Vista laptop. Thank you.

I had to uninstall dragdropupload because no matter how many times I tried to disable it, it wouldn't disable. Getting rid of dragdropupload did solve the problem, so thank you to all that suggested that solution.

I would have never associated this problem with dragdropupload, so how did you ever figure that out?

-Bill

Dragdropupload firefox addon was the cause. I have this problem too when I switched to FF15. First of all, in ff14 I crashed and then I was automatically updated to ff15 which I did not request for. When in ff15 if I close the first tab then the Pop appears: [JavaScript Application] Type error: Can't access dead object.

http://img338.imageshack.us/img338/6474/taccessdeadobject.png

It was an endless loop that would not close and I couldn't click on anything else. So I had to close out firefox through the TaskManager "End Process". It was solved by disabling the firefox addon Dragdropupload.

●All those that are reporting here about Dragdropupload as the problem need to inform this to the webdeveloper in the reviews: https://addons.mozilla.org/en-US/firefox/addon/dragdropupload/ ●And the firefox staff need to inform this webdeveloper too so that the addon will get fixed.

There is no drag & drop extension to disable! Can't say it was not helpful in that 30 others experienced the same dead object but none of the drag/drop/upload tools are listed in the browser.... So now wot?

Update: Okay, [whew] after a few hours of hit n miss, we found that 'resetting'/'restarting' Firefox with add-ons disabled was not very useful as the list of extensive add-ons required extensive reinsertion after we found the real problem was UP DATING PLUGINS! There were 2 issues with Java and an old Shockwave which required newer versions. So it seems the real solution is to break down and force yerself to accept 'Help' from the toolbar > 'Firefox Help' > enter 'Dead Object' [Search Mozilla Support] to bring yerself back to this page or merely look to the right lower side of the page for more info of CHECK YER PLUGINs! It was a challenge with restarts & discovery of the need to update but it would have been much easier than having to research, find, reorder & install the extensive list of extra special custom add-ons, extensions, theme & plugins provided by Mozilla Firefox again! It is amazing how much FoxFlags, FoxClox, Autofills, Animated AlienFoxWare & Bookmark Bar adds to efficiencies & smooth enjoyment. Tanx Mozilla Firefox!

Not really sure why but I ended up disabling my Fire Gestures (Tools -> Add-ons), restarting, and then enabling it back on and restarting again.

It's been working so far. Keep it in mind and hope this helps.