RosBE Crashes during compiling

I was compiling the shell-experiments branch with RosBE 2.1.1 and I keep getting this error (see attached picture). I was compiling ReactOS and then this error occurs randomly. This attempt was on 3997/8234 while the first time this happened was on 4245/8234.

My computer is running Windows Vista Business SP2. I have successfully compiled ReactOS and the shell-experiments branch many times. I noticed by typing ninja instead of ninja bootcd, it compiles. When its done I can type in ninja bootcd or ninja livecd and it works.