Exchange 2013 CU6 causing ECP 500 Unexpected Error

Hello,

After upgrading to CU6  administrator cannot log into ECP but it can access OWA. All other Exchange 2013 user can access OWA and ECP but the administrator can only access OWA and not ECP which gives a 500 Unexpected Error.

 I do iisreset /noforce and found error:

event ID 1000

Faulting application name: w3wp.exe, version: 8.5.9600.16384, time stamp: 0x5215df96

Faulting module name: rpcproxyshim.dll_unloaded, version: 15.0.995.21, time stamp: 0x53d064e3

Exception code: 0xc0000005

Fault offset: 0x0000000000003da0

Faulting process id: 0x55c8

Faulting application start time: 0x01cfe5522fe030ca

Faulting application path: c:\windows\system32\inetsrv\w3wp.exe

Faulting module path: rpcproxyshim.dll

Report Id: 8739d065-5148-11e4-80c8-d4bed9b65360

Faulting package full name:

Faulting package-relative application ID:

Please help!!

Thanks,

Server