hello, can you try to replicate this behaviour when you launch firefox in safe mode once? if not, maybe an addon is interfering here...

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Thank you Philipp. It's annoying that i have to click This doesn't solve my problem, as it probably does. I should have said i was disinclined to do that, as it just takes an eternity to then identify the miscreant addon by a process of elimination. I just wondered if any such was known to cause this behaviour.

could you just launch it in safemode once in order to confirm the addons-hypothesis? then it would obviously be helpful if you could list your installed extensions, maybe someone reading here came across the issue with one of those already - anything that goes into the direction of modifying tabs would obviously be a good candidate to look at first...

Thenk you. When i submitted the question i clicked the option to upload all the relevant details from my seetings etc, but that doesn seems to have worked. That option hasnt appeared since then. Isn't it working? Funny things do happen. Bloody MS apparently hijacks the'view in a web browser' option to IE! I'm sure youre right about someone having come across this issue before!