Unable to traceroute from one public IP to another

Has anyone experienced anything like this ...

I've been experiencing intermitent periods of time where I can't seem to reliably access my a system with one of my public IP's from another system with another public IP.

Specifically ... I can't seem to do a traceroute from one IP to another (I expect there to be one hop).

traceroute 50.73.x.37
traceroute to 50.73.x.37 (50.73.x.37), 30 hops max, 60 byte packets
 1  * * *
 2  * * *
 3  * * *
 4  * * *
 5  * * *
 6  *^C

My routing table is pretty basic ...

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
50.73.x.y       0.0.0.0         255.255.255.240 U     0      0        0 eth1
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
0.0.0.0         50.73.x.z       0.0.0.0         UG    0      0        0 eth1

Outside my network, there doesn't seem to be any problems.

One other thing that I've been observing, that may or may not be related, is that I've been having problems accessing my public IP's from systems attached to a consumer grade wifi router that's assigned to one of my public IP's.

Any suggestions on where I should investigate?

Thanks!

david