Try to create a new Boolean pref with the name network.manage-offline-status and set the value to false.

Right-click on the about:config page to open the right-click context menu and use "New > Boolean" to create a new Boolean pref.

Name: network.manage-offline-status
Value: false

To open the about:config page, type about:config in the location (address) bar and press the "Enter" key, just like you type the url of a website to open a website.
If you see a warning then you can confirm that you want to access that page.

• http://kb.mozillazine.org/about:config

Okay that didn't work. A message continues to pop up that says my add-ons are incompatible. I click the "check now" button and update the add-ons, but this never helps. The first time of every session this comes up and my setting are not saved and it is still offline.

Create a new profile as a test to check if your current profile is causing the problems.

See:

• Basic Troubleshooting: Make a new profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox