[@Shienvien] Which distro? Ubuntu, presumably? I dual boot Linux Mint, and I don't recall having this issue the last time I booted into Linux.

It doesn't seem to be an FF-specific issue, as I haven't had it, nor a site-wide one. It'd surprise me if it was an Ubuntu-specific one, as Mint is based on Ubuntu and it hasn't occurred there, either. It is extremely unlikely to be machine-specific, since it occurs on multiple machines for you. I suppose it could be caused by any plugins you may have installed in FF, or your internet connection? Not sure what else it could be, honestly, although I could very well be wrong.

Sorry I couldn't be of more help. Mahz might be better equipped to do so once he returns from RL.