Liquid> i have win8.1 x64 at home and bsetroot/bg worked fine. may be win8.1 32bit quirk.
Avail> i'll try to add some debug printouts in bsetroot/bg and we'll see what's happening.
for example when i use bsetroot/bg there is a quite long pause (1-3 seconds) before bsetroot sets really the color of the desktop. i find that annoying, this should be instantaneous...