This has happened to me before, with a way earlier version of Firefox anda also of WordPress.
I have been using Chrome, and in Chrome it works fine. But today I came back to Firefox and the same problem still manifests. I'm on a completely different computer than the first time, by the way.
What happens is that instead of doing all the steps of a download until the point where you can click "activate", it just says (e.g.)
Downloading install package from http://downloads.wordpress.org/plugin/contact-form-126.96.36.199.zip…
And then stops, doesn't show anything else.
The plugin can be activated, as it does go on the plugins list.
But this is annoying and I would love to overcome it. Usually I just click "Activate" on that same window.
Anyone can help?
Thanks very much.