What settings did you enable to get NT password support in the MDS Connection Service? I have followed the administration guide to the letter but the BlackBerry handhelds just timeout when executing HTTP lookups. The E-mail and PIM synchronization work perfectly.
Crowdie: Are you using proxy server to access internet?
If so, please try the followings:
Support HTTP Authentication = True
HTTP Proxy Enabled = True
Proxy Auto Configuration = False
MDS Authentication Enable = True