Can my neighbors or power company intercept my data over my powerline network?

You probably have a fault in either the wiring of the house, the device itself, or one side of the adapter pair isn't functioning.

This is the main disadvantage of Power-line devices.
1. Well firstly you need to make sure that the activity lights are ON on both the Power line adapters. 2. Don't use any Surge Protector or Extension cable, just directly to the wall. 3. Try in the same room first. 4. Power line devices works well where wall sockets are interlinked with common wiring as it is the mode of data transfer.
You can just power cycle the device, there is nothing much you can do about this. If its new device, get it replaced

There are two standards for powerline: HomePlug 1.0, which has a maximum link speed of 85Mbps and HomePlug AV, which has a maximum link speed of 200Mbps. You can use the two standards within the same building, but they are not compatible with each other.

HomePlug 1.0 - F5D4050, F5D4070. Powerline Turbo (F5D4071, F5D4073)

HomePlug AV - Powerline AV (F5D4072 + F5D4074 + F5D4077 + F5D4081). Powerline AV+ (F5D4075 + F5D4079) + Powerline HD (F5D4076 + F5D4078) and Powerline HD500 (F5D4085)

Your hard disk is failing and should be replaced. Have you tried to press F1 when you get the message? If this doesn't help try to enter the bios and disable S.M.A.R.T.
Your first goal is to save the data so please do that before it's too late.

Plug the PowerLine adapter into the wall
Plug one end of the ethernet cable into PowerLine wall adapter
Plug the other end of the ethernet cable into the Orange LiveBox
Plug the Orange LiveBox power adapter into the wall

try resetting the adapter
if not working try updating the firmware
if not working make sure ur adapter is pluged in the same power(electricity) phase of ur house with the router
the house will have different power phase so make sure of it
both the router and the powerline adapter must be in same phase of electricity

The top speed between the devices is 14 Mb/s, so they will never attain the 20Mb/s speed you had with you router / modem.

Netgear offers this FAQ for Powerline devices:

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• Powerline products work better when plugged into the wall without power strips, extension cords, surge protectors, or uninterruptable power supplies.

• Passwords. Powerline products have both a network password, and a device password. A particular device's password, which is not changable, is printed on the Powerline product label. Once you have collected all your Powerline device passwords, use the encryption dialog box, as described on pages 9 and 12 of the XE102 User's Guide, to change the network password. (Without password protection, it is possible, although unlikely, for someone very nearby to access your network.)

• If you changed the default network password, make sure that all the Powerline products use the same network password.

• If you've moved a Powerline unit, or disconnected the cables, your other network devices may need about 5 minutes to refresh their information about the Powerline's current status.

• If you have earlier Powerline products, switch to the encryption used by later products. (Early versions of XA601 and XE602 are known to have compatibility problems with newer models.)

• To test whether a house's electrical wiring is contributing to Powerline problems, plug units in the same room. Examples of potential problems are:
  
  • Old fuse boxes.
  • Old wiring that does not meet modern wiring building codes.

• Swap devices to isolate the problem to a particular Powerline unit.
• Reset the Powerline adapters to the default settings using the utility.

• Use all the same Powerline models for best connectivity. Also, software for one model may not work for another model. In particular, remote and advanced features may not work between Powerline manufacturers.

• Powerline is not directed at businesses, however it may work in a business environment, anyhow. See Assessing Powerline for Business Environments. In some cases noise can be limited by placing line conditioners or surge protectors between the source of the noise, and the Powerline units. (Not between the units.) Consult a professional electrician to evaluate your electricity's noise and to suggest remedies.

there wasn't actually any problem with the device. For these bridges to work, you need to be on the same phase of the wiring. If the devices are on different phases then they can't communicate. But I still couldn't get the encryption to work. Netgear support doesn't seemed to be bothered with that...they told me to ignore it.

Try to eliminate the problem into smaller parts. Try networking the two via the same power outlet via a multiple power board first in the same room. I don't have much experience with these powerline ethernet but i'm sure the configuration of these will be very similar as wireless router / access points and wireless adapter cards. However what I do know is that your power outlets need to be on the same "phase" of your electrical power system, so if you do this test I suggest (from one outlet board) you know the equipment works and your setup procedure works. then try seperating again and if it still doesnt work, check if your power outlets are wired on seperate phases (depends if your house has 3 phase wiring incoming to your home or not). Try another room or another outlet.

Our Powerline devices have security that will prevent anyone from seeing your Powerline network. Using the utility provided with the device, you can encrypt all data transfers over powerline to 56 bit DES. In addition, the range of the powerline signal is limited, in order to help prevent others from accessing the data stream.