KB Article: http://support.microsoft.com/kb/2655998
Consider the following
- You have a Windows Server 2008 R2-based Remote Desktop (RD) Session Host server in an Active Directory domain environment.
- You apply the Printer Redirection Group Policy setting to RD sessions that connect to the server.
- You repeatedly establish RD sessions to the server from a client computer that has multiple printers installed.
In this scenario, the logon time increases every time that you establish an RD connection. Additionally, the % Privileged Time count increases in the Svchost.exe process that hosts the User-mode Plug-and-Play Service (Umpnpmgr.dll) on the server. This behavior occurs every time that you log on, log off, or reestablish an RD session.
This behavior may cause performance issues such as slow boot, slow logon, system hangs, or failure to redirect printers and mapped drives.