There seems to be a (very small) time winodw when my pi will let me ssh to it. I got my computer to accept the new key and prompt for my password once (so it did connect), but I had forgotten to specify the user and I couldn't log in. Furthermore, the pi usually doesn't respond to ping requests. However, I can see that it has an active IP address on my router. Usually I get the "no route to host" error when I attempt to connect. Is this normal behavior? Do I need a better power supply or is something else wrong?
Note: I'm using the up to date raspbian wheezy image from here but I also tried the arch version and that didn't work either.
UPDATE: I tried hardwiring my laptop and sshing into my pi from my router but both attempts still produced the "No Route to Host" error. All the lights flash on the pi, but they eventually all turn off except for the power LED and sometimes the ACT light. From the router, I can see the pi establish anywhere from 0-5 connections during startup. However, they also end up going away.
UPDATE 2: I added a python script to my pi's /etc/rc.local file that would connect to my computer (which was running python's simple HTTP server) with wget and then ping my router. However, I never recieved any connections on my computer from the pi so I am beginning to suspect that this is a network/router problem. Are there any router settings that should be enabled for the pi?