.net will not run in the debugger because "unable to create local TCP / IP connection"

My project runs / debugs on my machine. On my partner machine, which works great with dozens of other shared projects, "the debugger failed to create a local TCP / IP connection, which is required for 64-bit debugging."

Understanding a bit, installing build on x86 "fixes" the problem, but that of course means that it is running the 32-bit version on my computer when the code comes back.

Does anyone know what might be causing this and perhaps a better solution?