I purchased a model B raspberry Pi in December. I don't have an HDMI monitor, so I figured I would get by using the device entirely through the network.
After imaging the raspbian hardfloat distribution, I powered it up and started running apt-get upgrade. Later I found that the three lights for the ethernet were all off, and I could not ssh into the unit.
This failure occurs randomly, and after being on for two weeks straight without incident, I thought things were better. I was wrong. This week I am having ethernet failures every 4-6 hours.
I read about possible problems with the voltage of the adapter, but it doesn't seem to be the case with my unit, since it doesn't happen with hi loads, it happens randomly while idle.
For what it's worth, I have a notion that it has to do with interference, because the only time I was able to reproduce the failure is when I placed a spare CDROM drive next to the power cable, and another time I moved an AM/FM radio alarm clock near to the Pi. On the other hand, I have it near a CRT monitor that makes a lot of interference when powered on, and that did not knock out the Pi's ethernet...
I think it is already too late to return it, and I feel disappointed that my only gateway to the device is unreliable... But perhaps it will help others to know that it's not just them having the problem.
UPDATE: Still irritated and curious, I got a multimeter and checked the voltages. With only the power and ethernet cables connected, the voltage is between 4.93 and 5.07V.
This is in the range expected, so no clear answer on the dying ethernet port.
To see if the 1000mA adapter is less-then-rated, I plugged in the USB charging cable of my half-dead cellphone and a USB mouse to see if I could make the voltage drop. I did get it down to 4.58 with the phone and mouse, but did that result in Ethernet dying? Nope, the Ethernet lights remained on, and I found I might still be able to make use of the Pi as a glorified USB cellphone charger...
I found that I can certainly kill the Ethernet plugging in a portable hard drive while charging my cellphone, but the Pi also reboots as the voltage dips to ~4.2V. After reboot, the Ethernet still comes back on, even with the hard drive trying desperately (and failing) to spin up...
Back to the cellphone and USB mouse, I did get the Ethernet to die within 15 minutes of powering on, but after re-plugging the power, it stayed on for another 2 hours, with the voltage around 4.5. The USB also dies each time, as I just discovered: the laser on the mouse turns off when the failure occurs.
It just doesn't make sense, there is no correlation between power drain & voltage and the Ethernet/USB failures.
UPDATE: I made a script that would run every minute, and reboot the Pi if the network was unreachable. This script never ran after the Ethernet failed, so actually the entire device is freezing, and I never could tell.
Knowing that the whole Pi is freezing, I rebooted and pulled the SD card out just as the Ethernet lights came on... Left it overnight and the problem eventually happened. That rules out any software on the SD card causing the problem.