Ok, now I'm experiencing the same problem. I have 8 nodes and 3 workstations all running Max 2010, XP 64-bit, Qube 5.5.0, and V-ray 1.50sp4a. One of the workstations gives the error "error initializing backburner path system". If I uninstall backburner, it says "unknown error starting program" instead when I try to render using Qube. Interestingly, when I copy and paste the command from Qube into a command prompt, it renders fine. Any ideas?