A deadlock occurs in Microsoft SQL Server when you import many users and groups in Microsoft Office SharePoint Server 2010. Additionally, the same deadlock occurs when you try to re-import. Therefore, you cannot import the users and groups.
To resolve this issue, apply the following hotfix package:
983497 Description of the SharePoint Server 2010 hotfix package (Osrchwfe-x-none.msp;Pplwfe-x-none.msp;Spswfe-x-none.msp): June 29, 2010