[nsp] bizarre 2950 behavior

[Matt Stockdale]

Hello-

 I've just brought up a new 2950 and I'm seeing the strangest behavior
on it. Despite having a configuration essentially identical to that of
one of the dozens of others we have in production, it is exhibiting the
following-

1) I can no longer telnet to it. On the occasions that it does answer,
it does not accept any password. It just seems to display the "User
Access Verification, Password:" prompt and then hang.

2) I can only ping it with alternating 64 packet runs. This boggles my
mind.

> ping a.b.c.d
PING a.b.c.d (a.b.c.d) 56(84) bytes of data.
64 bytes from a.b.c.d: icmp_seq=0 ttl=253 time=6.57 ms
64 bytes from a.b.c.d: icmp_seq=1 ttl=253 time=1.80 ms
64 bytes from a.b.c.d: icmp_seq=2 ttl=253 time=1.98 ms
.
. (all the packets between 3 and 60 are successful)
.
64 bytes from a.b.c.d: icmp_seq=61 ttl=253 time=1.77 ms
64 bytes from a.b.c.d: icmp_seq=62 ttl=253 time=1.78 ms
64 bytes from a.b.c.d: icmp_seq=63 ttl=253 time=1.79 ms
64 bytes from a.b.c.d: icmp_seq=128 ttl=253 time=1.78 ms
64 bytes from a.b.c.d: icmp_seq=129 ttl=253 time=1.92 ms
64 bytes from a.b.c.d: icmp_seq=130 ttl=253 time=1.61 ms
.
. (again, everything is ok here)
.
64 bytes from a.b.c.d: icmp_seq=189 ttl=253 time=1.81 ms
64 bytes from a.b.c.d: icmp_seq=190 ttl=253 time=1.83 ms
64 bytes from a.b.c.d: icmp_seq=191 ttl=253 time=1.83 ms
64 bytes from a.b.c.d: icmp_seq=256 ttl=253 time=1.80 ms
64 bytes from a.b.c.d: icmp_seq=257 ttl=253 time=1.81 ms
64 bytes from a.b.c.d: icmp_seq=258 ttl=253 time=1.79 ms

3) While the IP stack inside is clearly alive enough to listen to and
respond to pings (and partially answer telnet), I can't ping anything
from the device itself, even things within the same netblock.

This is actually the second 2950 I've tried to bring up in 2 days, the
first had different but also strange behavior. Both are running 

C2950-I6Q4L2-M, 12.1(13)EA1, RELEASE SOFTWARE (fc1), as shipped.

I'm totally baffled. 

Has anyone seen anything like this before? am I missing something
painfully obvious?

Thanks,
  Matt