Has anyone noticed intermittent flapping of AboveNet routes from Core-Exchange in Dallas?

Many of our clients that go through AboveNet for inbound routes will have intermittent packet loss or even 100% packet loss for up to 5 minutes at a given time.

For me, sometimes I will route through SanJose POP then back to the LA pop adding up to 20MS of additional latency. My ISP usually hands off at AboveNet LA POP, then straight to Dallas.

Any ideas?