"I have already done two system restores to fix this, but after each one the updates are once again installed and so the situation reoccurs."
Change the way your updates are installed - Windows Updates - under Important Updates change to Download Updates but let me choose whether to install them That way you have more control over them. (ie: I want what I want on my computer NOT what Microsoft thinks I should have)
If as you say System Restore fixes the problem then it is obvious that one or more of your updates is overwriting. Depending on how many updates there are, install one or two at a time - then restart each time and you should find the culprit.