It takes about an hour to complete the update; thereafter all works well.
After running win 8.1 upgrade I occasionally get msg. that system is updating PE but it never completes as far as I can tell.  Shows as running for about 15 minutes with 20 minutes remaining.  Update box disappears but then I notice TOO QUICKLY that there is an error msg. when I shutdown. Is there a way to verify that PE ran properly? Is there a way to view error msg's on shutdown?  They flash too quickly to read them. THANK YOU  
Updating PE Environment message after Win 8.1 Upgrade