System does not shutdown after upgrading to NIS 2011.

Recently upgraded to NIS 2011 from NIS 2010. Now the system does not shut down and power down. The specs are as follows:

 

AMD Opteron  (Quad Core) X 2

8GB RAM

Windows 7 Ultimate - 64 Bit

 

Did not have this problem with NIS 2010. The system now stays at Shutting Down screen and I can see minimal disk activity. But it does not power down completely.  I deinstalled NIS 2011 and cleaned up the system and the problem disappeared. After reinstalling, the problem reappeared.

 

Any suggestions?