Windows DUN doesn't connect with UM-150 in HDR only mode

Wild Bill

I've got a Verizon UM-150 that I connect to a WinXP box and then share that connection through the house with ICS. I set up and use a separate dial up connection than what VZAM creates so that Windows can connect itself whenever it needs to access the internet. This worked well for a while but since the leaves appeared this spring my connection has been switching between EVDO and 1X.

I have tried to eliminate the switching by setting the modem to "HDR only" mode. When I do that I can connect through VZAM just fine but Windows won't connect on its own. It will dial, say authenticating and then fail, and then try again, and fail, and try again, etc.

Any clues? Am I screwing anything up? Is this a typical issue people see with other modems? Does this just affect the UM-150? Or does it just affect MY UM-150?

All help is appreciated, thank you.

Bill