I'm experiencing this same problem directly on my T-Mobile MDA device (aka HTC Wizard). Apparently, one can also set the MTU on the device to work around this issue. I have not tried this yet.

I experience this problem on the T-Mobile network in Albuquerque, NM, but when I was in San Diego last week, I did not experience the problem.

My friend has the same phone on the same network, but with a different data plan. Her phone does not exhibit the problem.

My data plan is Unlimited VPN. Hers is the newer Total Internet plan.

T-Mobile has acknowledged this problem and is "working with Google" to resolve the problem. Obviously, it's a T-Mobile configuration problem, and apparently related to the data plan and network location.

I hope they find a resolution to this soon. If I find a workaround for the MDA, I will post it here.

Jason