Bombaywalla, is your Flash Player up to date, or at least not greatly out of date? For that matter, are your other plug-ins all up to date? That is easy to check in Firefox, as you are probably aware: Tools/Add-ons/Plug-ins/"Check to see if your plug-ins are up to date."
Also, try running Firefox in safe mode, as was suggested. If it works ok in that mode it most likely means that a plug-in or extension is causing the problem. You can then isolate which one is the culprit by disabling and re-enabling them (under Tools/Add-ons/Plug-ins or Tools/Add-ons/Extensions) until you zero in on which one precipitates the problem.
If there are a lot of plug-ins and/or extensions that are installed, the most efficient way of doing that would be with a binary search technique. Meaning disable half of them; see if the problem disappears; if it does it means that one in the disabled group is responsible; if it does not it means that one in the enabled group is responsible; then disable half of those in whichever group is responsible; and so on.
But the likeliest culprit based on my experience is Flash.
Best regards,
-- Al
