I have a very strange problem with our Sharepoint 2007 implementation. I went in today to grant access to a user and was greeted with "The user does not exist or is not unique." Let me start off by saying that this user is not on our domain we have a 2 way trust connecting to one of our subsidiaries.
I can see the users in the people pick but can't add them into Sharepoint. This problem flared up after we had some trust issues last two days ago. So I must ask has anyone came across this error and if so what steps did you take to resolve it? This link further highlights my problem:
Best Answer
Can you add the same user into other site collections? If so there may be an issue with the internal SQL table that stores the users for a site collection.
The Profile Synchronization timer job synchronises this data whith the user profile information. Check that the timer job is running.
Running several full imports from AD and then running the profile synchronisation may sort things out. If that fails, having a look at the raw user table in the content database may help in spotting an issue. However I reccommend only doing this on a backup of the content database, not on prod system.