Cannot Connect to internal IP addresses

My OSX 10.8 machine can no longer reach several machines on my home network's internal IP range. For example, I have an internal server which is also NAT'd through the router to accept SSH. The server is at 192.168.1.65.

~$ ssh 192.168.1.65 -v
OpenSSH_5.9p1, OpenSSL 0.9.8x 10 May 2012
debug1: Reading configuration data /Users/jakes/.ssh/config
debug1: Reading configuration data /etc/ssh_config
debug1: /etc/ssh_config line 20: Applying options for *
debug1: Connecting to 192.168.1.65 [192.168.1.65] port 22.
debug1: connect to address 192.168.1.65 port 22: Host is down
ssh: connect to host 192.168.1.65 port 22: Host is down
~$ ssh myDynDNSDomainToTheSameMachine
jakes@myDynDNSDomainToTheSameMachine's password:

The same thing happens if I try to RDP to another machine — similar setup. RDP to it's internal IP does not work. RDP to my dynDNS domain works fine.

It CAN connect however to the router and wireless access point IP addresses over http: 192.168.1.1 and 192.168.1.254.

Connection from other machines (including IOS devices) internally to other internal IP addresses works fine, it's just this OSX machine that has started to show this issue.

Can anyone offer any suggestions to troubleshoot?

EDIT: I found that I'm getting incomplete ARP entries:

~$ arp -a
? (192.168.1.1) at c0:c1:c0:65:c2:0 on en1 ifscope [ethernet]
homedesk (192.168.1.64) at 0:22:5f:2b:d:4c on en1 ifscope [ethernet]
raspberrypi (192.168.1.65) at (incomplete) on en1 ifscope [ethernet]
my-ipad-2 (192.168.1.77) at 1c:ab:a7:94:42:54 on en1 ifscope [ethernet]
home (192.168.1.254) at b0:e7:54:3d:c2:e9 on en1 ifscope [ethernet]
? (192.168.1.255) at ff:ff:ff:ff:ff:ff on en1 ifscope [ethernet]

Is that a problem on the OSX machine, the raspberrypi, or the router?