Problem upgrading to version 1.0.4
I'm running Firefox v. 2.0.0.14. It prompted me to upgrade my Zotero from the previously working version 1.0.3. I went ahead but the upgrade doesn't seem to have worked (Zotero is not visible in the browser window). If I look at "Tools" "Add-ons" it lists Zotero 1.0.4 and says it will be installed when Firefox restarts. Unfortunately restarting Firefox makes no difference to this. Any ideas? (Nb. I've also tried downloading directly from zotero.org, with the same outcome). I haven't tried uninstalling because I'm worried about losing my current information.
Also, uninstalling Zotero doesn't actually remove any Zotero data from your Firefox profile, so you can do that safely. But backing up your Zotero data is always a good idea in general.