SBS (and WHS?) if not dcpromo'd will, after seven days, shut down every hour. The process sbscrexe.exe is created by the SBCore service. If terminated it will immediately restart and it cannot be stopped. The service SBCore cannot be set to "disabled".
There are two (three?) ways to work around this. All will likely violate the MS EULA.
• Use Process Explorer to 'suspend' sbscrexe.exe
• Give Administrators permissions to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SBCore (and child nodes) and change the 'Start' DWORD from 2 to 4
• Deny the Everyone group all access to C:\WINDOWS\system32\sbscrexe.exe
• In Process Explorer kill sbscrexe.exe - it shouldn't restart
• services.msc should now show SBS Core Services as disabled
• An alternative approach is to disable the 'SBS Core Services' service in a particular hardware profile (ie can't do a outright disable) assuming there is only one hardware profile.
• Finally, repeated kills of the sbscrexe.exe process might completely kill it for a single session.
Edit - having an ntbackup process running in the background seems to stop sbcore from shutting down.