We are trying to install SalesLogix Mobile version 5.1.0.0 on Blackberry Curve # 8330 v 4.5.0.77.  Two of our intial three units loaded correctly, but the last unit receives the following error when attempting a full data synchronization:  "Sync operation 'InitializeSession' resulted in an HTTP response code of 400.  URL 'http://..."  The server settings are correct, and are identical to the other two units.  We have tried syncing from the Blackberry and from the Desktop Manager. 

  We are hoping to install this on 70(+) units after some initial testing, and would like to avoid these issues as much as possible.  Any thoughts?

I too am having this same issue, however this is on the initial sync of my first install.
Did you ever find a cause/solution?

We found that we had listed the Virtual root incorrectly on the Settings tab.  We had entered "sagesaleslogix" instead of "sagesaleslogixmobile". 

I hope this helps.