Maybe with all the worm and virus crap going on around the 'Net, it just can't get the bandwidth it needs to work reliably.
Just a thought, I don't know that much about what their system needs to get data through. When the first round of worm started spreading on my Comcast segment, I could barely get a ping through, let alone a steady stream of time-critical data (like Voice-over).
Whatever, good luck
Scott