I have 2 or three usenet providers that I switch between (mostly to get back posts on some that others don't carry).
Over the last 6-8 months or so, I've begun to have issues with Covad's service ONLY when I'm doing heavy Usenet traffic (downloading a TV show, large messages, or grabbing a lot of headers from one new group). If I'm doing this, Covad cuts off briefly (for about 5-10 seconds) and then comes back.
However, if I VPN somewhere else and do the same traffic via a VPN connection, it doesn't ever cut off.
I'm wondering if anyone else is seeing the same thing, or if I'm just lucky.