If your firefox browser always opening in work offline mode and want to get rid of it then here is the solution...
1. open firefox
2. Type in url about:config
3. click i'll be careful, i promise! (if it asks)
4. Find toolkit.networkmanager.disable by typing in the search field.
5. Change the value to true (double click)
6. Restart your browser.
Thats it "Happy browsing"...