Extension for Firefox

I’m trying to download and install an extension to my Firefox browser and I keep getting “Software installation is currently disabled. Click Edit Options…to enable it and try again.” message every time I click the Install Now button. When I click the Ed Op button the Options menu opens to the Content tab. Java is enabled, as is Javascript, and addons.mozilla.org and update.mozilla.org are allowed to install software. I can download files from other sites so what am I overlooking?

Firefox extensions have their own download process. What is the URL of the extension you are attempting to download?

Have you had Firefox installed since before version 1.5? If so, this link may help you. (requires setting option xpinstall.enabled to true).

Thanks to both of you for your replies. Nanoda, the info you provided did the trick. I did update to 1.5 from an earlier version so that was the problem. Thanks again.