Hello!

Have you tried reinstalling Firefox?

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Start Firefox in Safe Mode {web link} A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

He’s said that he already tried that.

Thanks for all your suggestions. However, such obvious stuff as re-installing FF from start, running it in safe-mode and using the Refresh FF function are all things i tried before posting this as an issue. i believe (of course could well be wrong!) that I've tied-it down now to some sort of conflict between FF installationn and my graphics installation (Nvidia GeForce 520). Why this should suddenly become an issue after years of faultless functioning has left me stumped ? Have now re-installed / updated my Nvidia graphics driver and (fingers-crossed) things seem a little better now. Robbie

I think that if graphic card had problem should happened with other programs too. I think also: What happens in pc when you open in Firefox a new window or tab? -> It use more memory (RAM). Maybe it's memory problem. If yes, check used/available memory level before and when this happens.

• edit

Note that, if/when you use "integrated graphics", graphics will using more CPU and tethering more MEMORY resources too.