This just happened to me when my cable internet went out so the roku couldn't reach the outisde world. The telnet login had this huge delay in loggin in and I also couldnt do an nfs mount. Now the internet is back up all is well. Maybe that is your issue too. Can't say I fully understand this, but hey I live in New Orleams the land of voodoo and other weird stuff!
After hearing this I would bet on it being dns! If this is still happening even when your internet is back up I would look at your dhcp server and see if it is handing out the correct address. once you connect to the roku cat the /etc/resolv.conf file and see what it points to and see if you can ping that address.