I am so glad I found this post and your answer! Occasionally over the years, Microsoft Windows security or stability updates result in lengthened "shutting down" page hangs (later updates usually have new versions and cure, but it's annoying meantime); this happened on Patch Tuesday of 01-08-13; this time I found your answer, and it's a great one!
I drilled to my regedit and found WaitToKillAppTimeout already existed, with a value of 8986; I reset it to a value of 3594 (about 40% of default time), rebooted, problem solved...my Windows 7 Home Premium now shuts down in the same time and rate as in six months preceding latest Windows updates. No known system/program jitters, no crashes as of moment, no BSOD(s).
So many other forums and blogs insist it's drivers, or the nonexistant-in-Home Premium grpedit.msc, which cause(s) shutdown screen hangs, it's easy to go asea...thanks again for giving such an obvious and effective short answer for 7 Home Premium users!
