I read the thread and created a new Firefox profile, reinstalled Zotero on that profile as Dan suggested to miluska some time back, and this finally allowed me to insert new citations into my document with Zotero.
Ok, I'm running 1.0.2.r2168 and I am not sure if this is development version or not, Firefox keep updating this.
I still get the same error message.
After removing Zotero and the extensions, and importing my backed up library it works fine on new documents. However, it's now saying that the citation no longer exists on older documents with more citations than I'd prefer to have to manually replace.
Will citations continue to be linked to ids?