Can you go to Menu>All>Firewall Configuration look under tabs Rules.
Is it blank/empty page ?
Edit -
I cannot look at that link at the moment.
Do you mean you downloaded the update manager and it is based on Linux Mint ?
It may be why it is not on the 3.4 in VirtualBox I used, as I only d/l the official etc, from Menu>Favorites>Install Updates
Edit 2 -
Ram is checked, do you have a sync tester, or a friend with it ?
Sync test - to stress the machines hardware and make the report of it, any faults.
Is it blank/empty page ?
Edit -
I cannot look at that link at the moment.
Do you mean you downloaded the update manager and it is based on Linux Mint ?
It may be why it is not on the 3.4 in VirtualBox I used, as I only d/l the official etc, from Menu>Favorites>Install Updates
Edit 2 -
Ram is checked, do you have a sync tester, or a friend with it ?
Sync test - to stress the machines hardware and make the report of it, any faults.