Unable to access remote path

On a whim (or by desperation), I ssh-ed into my NAS and tried a simple ping. Ping is resolving to the wrong IP address. The correct IP is 192.168.1.70, but it's resolving to 192.168.1.102. If I replace the hostname in the backup form with the IP address, it works.

I has this same issue just a week or so ago (viewtopic.php?f=31&t=74353). I thought this was caused by me changing the router on my system temporarily, and the problem resolved itself without me doing anything after 24+ hours. But now it's happening again. ??

As per the advice on that other thread, I tried "arp -a" with the following results:
turks:/usr/bin# arp -a
StThomas (192.168.1.102) at <incomplete> on eth0
www.asusnetwork.net (192.168.1.1) at 08:60:6E:CB:77:C8 [ether] on eth0
? (192.168.1.108) at <incomplete> on eth0
? (192.168.1.70) at 30:F9:ED:43:8F:27 [ether] on eth0

Notes:
* "turks" is my NV+
* "StThomas" is my PC. It's actual IP address is 192.168.1.70 -- not 192.168.1.102
* I see both of these address listed in the arp -a output, with .102 showing as "StThomas", and .70 showing as "?"
* Hardware topology-wise, both the NAS and StThomas are connected directly to my router via Ethernet. The other systems, which are working fine, are connected via Wifi.

I've then issued "arp -d 192.168.1.102, and it completes without output.
Attempting another ping still resolves to 192.168.1.102.

For completeness, here's a copy/paste of the output from the following commands
* arp -a
* ping
* arp -d
* arp -a
* ping

turks:/usr/bin# arp -a
StThomas (192.168.1.102) at <incomplete> on eth0
www.asusnetwork.net (192.168.1.1) at 08:60:6E:CB:77:C8 [ether] on eth0
? (192.168.1.108) at <incomplete> on eth0
? (192.168.1.70) at 30:F9:ED:43:8F:27 [ether] on eth0
turks:/usr/bin# ping stthomas
PING stthomas (192.168.1.102) 56(84) bytes of data.
From turks (192.168.1.103) icmp_seq=1 Destination Host Unreachable
From turks (192.168.1.103) icmp_seq=2 Destination Host Unreachable
From turks (192.168.1.103) icmp_seq=3 Destination Host Unreachable

--- stthomas ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3012ms
, pipe 3
turks:/usr/bin# arp -d 192.168.1.102
turks:/usr/bin# arp -a
StThomas (192.168.1.102) at <incomplete> on eth0
www.asusnetwork.net (192.168.1.1) at 08:60:6E:CB:77:C8 [ether] on eth0
? (192.168.1.108) at <incomplete> on eth0
? (192.168.1.70) at 30:F9:ED:43:8F:27 [ether] on eth0
turks:/usr/bin# ping stthomas
PING stthomas (192.168.1.102) 56(84) bytes of data.
From turks (192.168.1.103) icmp_seq=1 Destination Host Unreachable
From turks (192.168.1.103) icmp_seq=2 Destination Host Unreachable
From turks (192.168.1.103) icmp_seq=3 Destination Host Unreachable

--- stthomas ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3012ms
, pipe 4
turks:/usr/bin#