Hi Uri,
You have mentioned an important point, "that user from other users is that he was created today."
Have you had issues earlier when you created a user in the AD and on the same 'day' the CRM User was unable to login?
If yes, then did you have multiple DC's (at that time) or you still have it; reason may be related to the sync.
If No, Can you try add (say) a test user in the AD and retrieve it immediately in CRM via the 'User Wizard'. If not, then there are sync issues wiith the DC. If not, then the problem exists within this specific user. (you could also give a shot to point no 6 of Mohammad Atif;s above post)
If the above two options still dont' work, you need to try the (usual savior) CRM Diagnostic Tool which you download from https://crmdiagtool2011.codeplex.com/. Generate the file and if the case exists, try sharing the file on the forum.