>>1777679I know I'm super late to this but you've helped me in the past so I'll try and help you back :).
I was having this issue a couple of days ago and this seemed to stop the pink box from showing up. Here's a link to my .Xdefaults which, in my case is located at C:\cygwin32\home\Craig
If you know how to get font's working with urxvt in windows then I'd appreciate your help.
https://dl.dropboxusercontent.com/u/2177569/.Xdefaults