One of my colleague pinged me with a strange problem he was encountering in user profile property mapping. He wasn't able to add or edit user profile property import mappings because the 'Data source field to map' drop down and the 'Enter field to map' text box were missing from the 'User Profile Property' page in SSP. The page was coming without the dropdowns and showing 'The selection of directory service properties is disabled because the portal is in an untrusted domain or no directory service import is configured yet';
I initially thought it to be some issue with security permissions on reading some specific AD attributes. But that was not the case as he has succesfully imported the profiles from AD. Later on it was realized that the account under which he was running the SSP was a local box account and not a domain account. While importing profile he was prompted for domain account for importing profiles, that's why he was able to succesfully import the profiles. But when the profile property page tried to connect using the SSP account, it failed and hence disabled the drop downs.
So if you are facing this issue, just make sure that the account used for import has read access to the directory store which generally the domain accounts will have.