I had read that the Guruplug wasn’t particularly reliable as a wireless network client.  There are instruction on making it behave as a reliable client, which I had followed when I set up the wireless networking.  However, today the wireless networking hung.  I have two network connection to the Guruplug.  I have the wireless connection, and I also have a wired connection to a router configured as a wireless bridge.  I could still log in using a wired connection, so I could see the Guruplug wasn’t dead.  Unfortunately although there were two network connections to choose from, it insisted on using the hung wireless connection.  So I edited /etc/network/interfaces to disable the wireless on the Guruplug.  I’ve used the bridge for several years and had no problem with it, so hopefully the hardwired connection will hold up.  I’ll let it run and see how it does.