Had an issue with a clients laptop not booting into Windows – after some debugging, found STOP message as below:
STOP: C0000135 Program can’t start because %hs is missing. Try reinstalling the program
Turns out an AVG update is the cause. To resolve, follow http://forums.avg.com/ww-en/avg-forums?sec=thread&act=show&id=132999
Also make sure to run startup repair before booting into the OS.