Peering Issues with Global Crossing and SBC?

All,

I have well over 150 vpn customers but this past week I have had 7
customers ipsec tunnels constantly bouncing all day. The common ground
for all 7 of these customers are traversing the SBC and Global Crossing
links you see below, the ultimate common ground being 64.208.110.29.

9 151.164.191.134 16 msec 16 msec 16 msec
10 64.208.110.29 16 msec 16 msec 16 msec

9 151.164.40.49 16 msec 16 msec 16 msec
10 64.208.110.29 12 msec 20 msec 12 msec

When tracing to these 7 customers all 7 hit one or the other of the
trace's you see above. I have opened a ticket with SBC but no answer
from them yet. All of the other customers have been very stable and of
course non of the other customers traverse either of these links either.

Anyone from Global Crossing or SBC that could contact me off list or
lend a hand it would greatly appreciate it.

Thank you