Windows Phone 7 Beta: ProgressBar.IsIndeterminate="True" breaks my JSON calls

Question

This is the weirdest thing I've seen in a long time...
I have a simple application that makes some JSON calls to a server and processes the results, this takes a little while so I was planning to add a progress bar to indicate that something is happening.
This all works fine if I leave IsIndeterminate="False" however when I set it to True my JSON calls fail with
"The remote server returned an error: NotFound." {System.Net.WebException}
Anybody got any ideas what might cause this? I'm wondering if it could be a bug in the Beta tools?

Answer 1

I'm guessing you're using the public release of the tools. In which case the indeterminate progress bar implementation has been found to use huge quantities of processor time. This is probably killing your networking.

I hope they will fix this for the proper release.