I'm running Win.7.  After trouble with a file that my A/V prog found and removed, plus Plug-Ins, but still left an undesirable that wasn't listed in Control Panel I attempted a System Restore. It went thru the process and on re-opening says its hadn't been successful. I re-tried several times and with older dates, but same results. 
After many run-around red-herrings one outcome was that when trying to re-install Win.Essentials 2012 it failed at ~48% whilst at Messenger, some times saying Try Again, sometimes saying it couldn't install whilst another prog (or download -?)  was still ongoing.  I went thru this cycle  several times, sometimes for just selective progs in Ess'l, (MM and Photo Gallery,) sometimes for all Ess'l progs, - same result. Still never completed.
Finally I went back to a 'Undo Restore' point and now have Win.Live Mail, Ph.Gallery and Movie Maker back in the prog list but the latter is not working and comes up with 'Directory name is invalid' - but no code given. 
I suspect I'm short of some Plug-In, Add-On, or DirectX (whatever that is, - I saw it ina list,) but dont know how or where to start on these aspects.
Please advise.
CJ