How to fix Firefox 3.0 auto-launch for some files
You may have noticed that Firefox 3.0, in a change from 2.0, does not auto-launch some files correctly like Word documents (doc), spreadsheets (xls), torrents, nzb, etc.
Here’s how to fix it:
1. go into about:config
2. create browser.helperApps.deleteTempFileOnExit
3. set it to boolean: false