Q: I cannot add new bookmarks in my Firefox browser. This just started a few weeks ago. Any suggestions? —Harry I.
A: There are a number of reasons this might happen. First, before anything else, make sure you're running the very latest version of Firefox. You can download it from www.getfirefox.com. According to the Firefox knowledge base, an add-on called Bookmark Duplicate Detector can cause this problem. So if you have that installed, remove it.
Another possibility is that the file holding your bookmarks has been labeled read-only by accident. Launch Explorer and navigate to C:\Documents and Settings\username\Application Data\Mozilla\FirefoxL\Profiles\randomstring.default. If you're running Vista the location is C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles\randomstring.default. Find the file Bookmarks.html in that folder. Right-click it and choose Properties. If the read-only box is checked, uncheck it.
Still not fixed? You may need to reset the local store. Close all Firefox windows, then click Start, click Run, and enter firefox-safe-mode. In the box that pops up, check the option Reset toolbars and controls and click the button Make Changes and Restart. You can accomplish the same thing by deleting the file Localstore.rdf from the same folder where you found the bookmarks file.
I hope one of these techniques solved the problem. If you're still in a bind, though, Firefox's own support site has a page devoted specifically to troubleshooting bookmark problems. (story Link)