XP operating system. 'Have two copies of Firefox. The first is on C:; the second is on an external drive (Passport). 'Am using Portable Firefox on the Passport. When I upgraded the Portable Firefox from 3.6 to 4.0, I could no longer see my library. Read Zotero web page "Troubleshooting Zotero Data Issues: Where did my items go?" I was able to find two locations with .sqlite, but I don't know how to use that information to correct the problem. My assumption is that one of the .sqlite paths is for the laptop Firefox and that the other is for the Passport, Portable Firefox, copy. I am not computer savvy, and I am reluctant to do something that might cause the loss of my thesis info. Is there additional information formatted in a step by step process for this particular problem. I have to believe that there are others who are external drive dependent and thought that updating Portable Firefox was a non-issue. Additional symptom: When I launch Portable Firefox, it indicates that it is 3.6 but when I check the version of the Firefox that is launched it indicates that it is 4.0.