After installing the Public Fox extension to Firefox, the previously installed Zotero add-on began having problems. It would load the following error: “There was an error starting Zotero” with a yellow hazard triangle and exclamation mark on the Zotero logo in the status bar.
If you disabled the Public Fox extension and restarted Firefox, Zotero started up without error. You could then re-enable Public Fox and restart Firefox and have no problems.
Upon restarting (restoring the profile), the Zotero problem would return.
Under the Firefox profile (C:documents and settings[username]Application DataMozillaFirefox…), I deleted compreg.dat and xpti.dat. These two files are regenerated upon the next startup of Firefox.
I started up Firefox and Zotero was working perfectly along with all the other extensions. I deleted the two .dat files from the profiles of other identical machines that were also having this problem with Zotero. After those files were regenerated, Zotero worked perfectly.