problem connecting to my linus server with rsa keys through Putty on Windows

[Scott Berry]

Hello there,

I am trying to connect to an ssh server on my linux machine via putty on a 
Windows machine.  I followed the instructions and made an authorized_keys2 
file and ensured that the permissions were correct with ls -0lr.  Here are 
my permissions:
[root at pilotalk .ssh]# ls -lr
total 8
-rw------- 1 root root 223 2007-07-20 09:51 authorized_keys2


Now when I connect using my Windows machine to get in to root for my linux 
server I get the following error coming I assume from the linux server:
PuTTY Fatal Error
Server unexpectedly closed network connection

What would be the most probable causes for this?  Everything looks perfect.

Scott