I can't copy and paste. Try to follow instructions to fix, but get stuck.
How do I fix this? I tried to follow the instructions, but when I get to the part of copying the lines of text they give me, I , of course, can't. Help please. Unprivileged scripts cannot access Cut/Copy/Paste programatically for security reasons. Click OK to see a technical note at mozilla.org which shows you how to allow a script to access the clipboard.
Alla svar (3)
You should be able to select text on any page and copy using Ctrl+c or right-click Copy or using the Edit menu. If you get that permission error even on this site, then I suspect you have an add-on that is intercepting these normal functions.
To diagnose add-on issues, you have a couple of different options.
First, make a backup of your computer for safekeeping. To back up Firefox, see Backing up your information.
Next, try starting Firefox in Firefox Safe Mode. Be careful not to "reset" anything permanently if you didn't back up.
Does that fix it? If not, try creating a new (blank) profile: Managing profiles.
If the new profile works correctly, you can go back and selectively enable/disable add-ons, or move key settings like bookmarks from your damaged profile to the new profile. For that, see: Recovering important data from an old profile.
Oh, and be very cautious giving sites permission to copy the clipboard in prefs.js: you may have placed sensitive information on the clipboard that you don't want other sites to access.
Hmmm, board won't let me edit my post...
IF THIS ONLY AFFECTS ONE SITE, then feel free to post the URL so others can test and advise.
Did you try to use Ctrl + C to copy and Ctrl + V to paste (Edit > Copy / Paste) ?
See http://kb.mozillazine.org/Granting_JavaScript_access_to_the_clipboard
https://addons.mozilla.org/firefox/addon/852 - AllowClipboard Helper