After a freeze-up of my Mac, I had to have Leopard reinstalled. Now I can't open Zotero. I get an alert saying: "There was a problem starting Zotero." Any thoughts?
Follow the steps in the Advanced Instructions section of the Reporting Bugs page and let us know what appears in the Error Console.
If you had specified a custom database location, type about:config in the Firefox address bar and reset the pref extensions.zotero.useDataDir to false. You should then be able to start Zotero and reselect the data directory in the Advanced pane of the Zotero prefs.
After resetting the useDataDir pref, you may also need to delete (with Firefox closed) the files compreg.dat, xpti.dat, extensions.ini, extensions.cache, and extensions.rdf from your Firefox profile directory. They'll be recreated when you start Firefox.
Upgrade Storage
If you had specified a custom database location, type about:config in the Firefox address bar and reset the pref extensions.zotero.useDataDir to false. You should then be able to start Zotero and reselect the data directory in the Advanced pane of the Zotero prefs.