I have had almost no problems with the new software until yesterday when I found it impossible to post any replies or new threads in Firefox. Today I switched over to IE and here I are

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In Firefox (latest update) no matter where I click on a reply button I get a square box rather than a rectangular one and it lacks the headers across the top for font, underlining, centering, adding links and pictures etc. The blank will not accept any keystrokes nor can I paste from another text source, although I can post a blank message. This is true for the Quick Reply box, also.
If I right click on the box I get options like 'save this frame,' 'show this frame only,' etc.
Any ideas what to do? I much prefer to use Firefox and haven't even updated IE for over a year now as I never use it.
Besides Firefox I'm on Windows XP. I get no error messages.
I've tried deleting cookies, clearing cache, rebooting repeatedly, nothing makes a difference.
Oh yes, when I tried to sign out yesterday, I was repeatedly taken to a page headed 'you have reached a page for Roadfood Insiders only' and I am not a Roadfood Insider and I was not logged off. I tried so many things I can't remember how I finally managed to sign out.