"Bad network path" from data colector

Hi people!
I'm using a Data Colector LXE with Windows CE v5, connected by wireless conection with a dinamic IP using DHCP. It's conected to Windows Server 2008 Standard, that run as File Server, DHCP and DNS services and is a Domain Controller.
I can access internet and "ping <local ip>" works ok. But when try to access shared folder by "\\<ip>" or "\\<hostname>", I have the follow message:
"Bad network path. Check to see if the path you typed is correct and that your dial-up connection is active or your network card is properly inserted."
Its fun, because I could access 2 weeks ago normaly.

Help us.
Thanks.

"and is a Domain Controller"

By default DC's under 2008 are set to require signed kerberos authentication, which CE cannot participate in as it does not engage in AD. You will have to lower your network security considerably to resolve this. This is why it is recommended practice to separate DC's from production servers.