Ping Works but Connection Fails

I'm having a perplexing problem with a Windows 2000 Server TCP configuration
I need help understanding.

I have a device on 10.1.5.55 I need to configure. I set my Windows 2000
box to run class B on 10.1.5.1 and set the gateway to 10.1.5.55. After
directly attaching to the device I want to configure by a crossover cable, I
am able to ping from the Windows host to 10.1.5.55 and get an ICMP response
no problem. Arp -a confirms the mac address of the responding device is my
intended target.

Now I try to telnet to the device and I get an *immediate* connection
failed, not at all the normal timeout I associate with a host that does not
run telnet. I start up a sniffer, and sure enough with ping I see the
back and forth ICMP packets. With telnet, the TCP SYN packet NEVER LEAVES
THE ETHERNET INTERFACE of my Windows 2000 host. There is no other ethernet
adapter on this Windows 2000 box for this packet to travel to. Where is
the missing packet? Why is Windows 2000 immediately failing on the Telnet
connect attempt? I ran netdiag but didn't see anything interesting there.

Any insights into this strange behavior are appreciated.

--
Will