JHMcG may have misunderstood your initial question as it related to the topic title. I did until I read your second reply which clarified your question.
Many of us do not recommend disabling System Restore as the first step when attempting to clean a system or when scanning for malware. Unfortunately, some anti-virus vendors still recommend doing this before attempting malware removal and many folks follow that advice.
ComboFix attempts to create a new System Restore point as an added safety net. There is always the possibility of something going awry during the malware removal process and you can end up with more serious problems than the original infection. If restore points are available, you can use System Restore to return the computer to a previous working state and hopefully regain some stability. Without a restore point to fall back on, you are left with a limited means of restoring your system to a usable condition. Although System Restore is not always 100% guaranteed to work all the time and it may restore some malware, it at least gives you another option
before resorting to more drastic measures.
ComboFix /Uninstall resets System Restore...clears the System Restore cache to prevent possible reinfection and creates a new Restore point.