However, I've recently started to have a problem that I've not noticed before (possibly as a result of updating to the newest versions; I'm now on 2.17d, but it was happening with 2.17c, and maybe before that, I don't recall). Whenever Fast Dial opens, either as my homepage on startup or in a new tab, it resizes my browser window from maximised to a small square. If I unmaximise manually, resize the window to a large square, and then open FD, it reverts to the small window again. This is happening on both my desktop (which has many extensions) and my laptop (which has none)

How strange
Especially to have on both machines

I wonder if the following might help
Maximise Firefox so that the browser is as you wish then top right click close.

Maybe it will remember that setting.

Also might be worth checking your settings by rightclick/Properties on your Firefox start up icon and check settings there.

Please also have a look at this link

It discusses this problem

Please let us know if things improve

Many thanks