It sounds like the VC6 compiler (what the Make VC6 action calls to build a VC6 project) is terminating abnormally for some reason in this scenario. One possibility would be a DEP issue (see
http://www.kinook.com/Forum/showthread.php?t=3598). You might also make sure that you are running the very latest VC6 release + any hotfixes. Other than that, I can't think of any solutions except avoiding starting RDP with a VC6 build compiling, since I doubt Microsoft is updating VC6 any longer.