2008 R2 - Memory Leak from svchost.exe - Module "rpcrt4" is the culprit

Hi All

Over the past week or so (after a set of Windows updates and restart) svchost.exe has increasingly used more and more memory. It probably gobbles up an extra 1GB per day and doesn't relent. 

After running various diagnostics, the debug diagnostic tool finally provided me this information after a memory leak test:

rpcrt4.dll is responsible for 1.76 GBytes worth of outstanding allocations. The following are the top 2 memory consuming functions:
rpcrt4!AllocWrapper+2b: 1.76 GBytes worth of outstanding allocations.
rpcrt4!Ndr64ClientInitialize+964: 1.36 MBytes worth of outstanding allocations.

Detailed module report(Memory)

Module details for rpcrt4
Module Name   rpcrt4 
Allocation Count   946941 allocation(s) 
Allocation Size   1.76 GBytes 

Module Information 
Image Name: C:\Windows\System32\rpcrt4.dll   Symbol Type:  PDB 
Base address: 0x00000003`00905a4d   Time Stamp:  Sat Nov 20 13:13:18 2010  
Checksum: 0x00000000`00000000   Comments:   
COM DLL: True   Company Name:  Microsoft Corporation 
ISAPIExtension: False   File Description:  Remote Procedure Call Runtime 
ISAPIFilter: False   File Version:  6.1.7601.17514 (win7sp1_rtm.101119-1850) 
Managed DLL: False   Internal Name:  rpcrt4.dll 
VB DLL: False   Legal Copyright:  © Microsoft Corporation. All rights reserved. 
Loaded Image Name:  rpcrt4.dll   Legal Trademarks:   
Mapped Image Name:     Original filename:  rpcrt4.dll 
Module name:  rpcrt4   Private Build:   
Single Threaded:  False   Product Name:  Microsoft® Windows® Operating System 
Module Size:  1.18 MBytes   Product Version:  6.1.7601.17514 
Symbol File Name:  c:\symcache\rpcrt4.pdb\7D748DA6D7454C9EA38C8CEF1C9E75F22\rpcrt4.pdb   Special Build:  & 

rpcrt4!AllocWrapper+2b  has 944,468 allocations! 

I'm running 2008 R2 64bit with anywhere up to 80/100 simultaneous RDP connections at any one time.

Can anyone help or advise as I cannot find any hotfixes for this issue.

Thanks

Ryan