There can be many problems with an install of the new Active Sync 4.1 from Microsoft.
For those of you who are not faint of heart a visit Chris De Herrera's web site (outsde Symbol) at
Pages 12 on give details of just some of the problems that might be encountered !
Two other important points worth noting though.
1) When installing ActiveSync onto a PC it is often worth while NOT being part of any Domain when you do so. This always seems to work more reliably. Usa a local Admin account.
2). The Active Sync internal IP addresses have changed from 192.168.55.100/101 to 169.254.2.1/169.254.2.2. This should only be of interest if you are actively allowing/blocking ports on the PC but may be relevant for IP routing questions on the terminal.