Adobe error in PDF operations

Hi,

Can you please help me to resolve the Adobe issue when I use the code Acrobat.AcroAppClass.CloseAllDocs().

the error message is System.Runtime.InteropServices.COMException: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

Also I am getting an event log

Faulting application name: Acrobat.exe, version: 15.6.30119.36332, time stamp: 0x56740a62

Faulting module name: ntdll.dll, version: 6.3.9600.18233, time stamp: 0x56bb4e1d

Exception code: 0xc0000374

Fault offset: 0x000e6054

Faulting process id: 0xee4

Faulting application start time: 0x01d1f8ad4f11f4b3

Faulting application path: C:\Program Files (x86)\Adobe\Acrobat 2015\Acrobat\Acrobat.exe

Faulting module path: C:\Windows\SYSTEM32\ntdll.dll

Report Id: 8e8d79bd-64a0-11e6-8103-005056ae5229

Faulting package full name:

Faulting package-relative application ID: