Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).
See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears.
You can use "Disable all add-ons" on the Safe mode start window to disable all extensions.
You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Bismillaah. Peace. Thanks cor-el, for the reply. I've copied it for future reference. Unfortunately the problem is external. Someone in or near this building is tampering with my pc. This morning Adobe Flash plugin failed. I've tried reinstalling it but it will not work. I dual boot win xp, and all is well on that drive with the latest update of firefox. But at this point I'm wondering why I'm being forced to quit Ubuntu? Will advise if there are improvements. Abdul

Bismillaah. Salaam/Peace. Adobe Flash plug-in is back in service, some two days after I'd re-installed Firefox. It did not show any improvement the first day, for whatever reason, I cannot explain. No change in automatic scrolling at some sites. Abdul