To see if my GuruPlug works fine (since I heard about rebooting issues and network problems), I just let it run over night, of course with my USB-fan running to assure a good air flow. The next day, everything was fine as far as I remember but when I tried to connect to my USB hard drive, I figured out that my USB ports don't work any more. There is no 5V power and also an external USB-drive does not work, neither does the SD card.
Now I am wondering what could have happened. Did the constant 80mA of the USB-fan destroy the USB-interface? That should be impossible since the USB specification requires a current up to 500mA, and it's running on my PC's USB for a few days now without problem. Is it a heat problem which made my USB die? or did I mess up some configuration? Since I do not want to loose warranty I did not open my plug yet. It might just have burned some part which is easily replaceable, but if I can't fix the problem without opening the case, I will first try to return it before I do anything else.
To figure out if I messed up the configuration, I decided to re-flash my GuruPlug. This is also a great possibility to get to know the boot process better and get some insight into the file system. The tutorial I am following is the reflashing-tutorial on plugcomputer.org. It seems to work, but I am having some troubles getting the root file system to the plug using tftp. Here are my experiences with tftp and the installation process. I also added a short tftp-tutorial.