When I tried to do a system restore recently, it ended up with a message that 'an unspecified error ocurred using System Restore'.
So I rebooted, and entered the WinRE environment and from there, with N 360 not running, the operation succeded.
After rebooting, N360 showed this error:
which confirms my belief that N 360 is the root cause orf the problem.
Effectively disabling using System Restore from a normal user session in Windows is not acceptable behavior for a reputable Windows application.
You should investigate this, and either - if Tamper Protection causes this - ammend the Help and Support to advise users to disable it before using System Restore, or if it fails in every case, do something about it, and do it fast.