Logged in through IE to post again.
I can't say I enjoy having it pointed out that I alone have issues with Firefox. However, I am a competent and experienced web user, and have been a member of various "forums" or bulletin board sites since 1995. I have never had issues like this and still today on other websites I have no such issues.
What I have done to attempt to resolve this (and why I am really probably now giving up) -
1. Checked all Firefox settings and deleted all cache and cookies. Re-started computer & Firefox, no resolution.
2. Downloaded latest version of Firefox (3.0.8) even though the upgrade to 3.0.7. had only been done "automatically" a few days before. Re-started computer and Firefox, no resolution.
3. Re-checked all settings in Firefox, re-started, no resolution.
4. Checked all settings in RF and changed to full-screen reply, from pop-up. No resolution.
5. Turned off anti-virus s/w and firewall, re-started Firefox, no resolution.
I have tried other solutions as well, and tested many websites, and have no problems with other sites, but (obviously) no resolution here either.
Interestingly, when I click on "Reply to message" with "quote message", you would think that it would at least place the quote in a box or on the screen but no quote appears. I used to be able to post with quotes.
Two more items:
a) I did not update Firefox or change settings and then have this problem appear, it appeared "out of the blue" for me. Though I do regularly upgrade my browser, I checked the dates and they don't coincide.
b) I actually am now having problems with 3.0.8 that I did not have in previous versions, that is several websites that used to load quickly act as though they are "still loading" when they are not. This does not happen on RF, but it does happen on may Yahoo sites and also on sites without any advertising. (I originally thought it was the Yahoo advertising, which could still be an issue... as it could here as well.)
Okay, that's it. I didn't mean to or want to but I spent many hours trying to resolve this. Thanks to Tony for his advice and to Al for his help.
No thanks to other tech admins here who don't even acknowledge my posts, much less address my issues. I'll slink back to Firefox now and leave you all in peace.
Best wishes to all Firefox users - may you not have the problems that I have!