How did you setup the profile in the first place??
Very Very important information. Otherwise, we have to ask, "Did you turn on the DC?" :)
To create a roaming profile:
Open Active Directory Users and Computers and connect to the Domain Controller. Or just login to the DC itself and open the AD Users and Computer
Right-click the user account and then choose Properties => Profiles.
Type the path into Profile path, like
Romaning profile folder
Make sure the share is accessible to that User also.
You can also get a log of the User's login and see where it breaks.
Look under their registry:
Make an Reg_DWORD called UserEnvDebugLevel and set it to HEX 0x30002.