services.exe is trying to modify a protected registry key

Hi everyone,
I am using CIS 5 on Windows 7 and all went well. But today everytime I startup my PC COMODO Defense+ ask me for permisson that services.exe (C:\Windows\System32\services.exe) is trying to modify a protected registry key HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\EFS. I had allowed that. I also have noticed from a registry backup that the value of “Start” was 0x00000003 (3) before modification and now its 0x00000002 (2). Now I want to know is it safe to allow this request or I should block this request?
Plz, help.

Thanks, for your help.

It is changing a key for Encrypting File System. Since we cannot see what program is calling services.exe I can only assume it is something Windows is doing its self when you are free of malware.