This indicates an attack attempt against a Denial of Service vulnerability in Microsoft Remote Desktop.
The vulnerability is due to the Remote Desktop service listener going to sleep for 30 seconds when a client closes a connection by sending a RST packet, and during this time, no new connections can be accepted by the server. Successful attacks may cause the target Remote Desktop service to stop accepting new connections, resulting in a Denial of Service condition.
Windows XP Service Pack 3
Windows XP Professional x64 Edition Service Pack 2
Windows Server 2003 Service Pack 2
Windows Server 2003 x64 Edition Service Pack 2
Windows Server 2003 with SP2 for Itanium-based Systems
Windows Vista Service Pack 2
Windows Vista x64 Edition Service Pack 2
Windows Server 2008 for 32-bit Systems Service Pack 2*
Windows Server 2008 for x64-based Systems Service Pack 2*
Windows Server 2008 for Itanium-based Systems Service Pack 2
Windows 7 for 32-bit Systems and Windows 7 for 32-bit Systems Service Pack 1
Windows 7 for x64-based Systems and Windows 7 for x64-based Systems Service Pack 1
Windows Server 2008 R2 for x64-based Systems and Windows Server 2008 R2 for x64-based Systems Service Pack 1
Windows Server 2008 R2 for Itanium-based Systems and Windows Server 2008 R2 for Itanium-based Systems Service Pack 1
Denial of Service: Remote attackers can crash vulnerable systems.
Apply patch, available from the web site