Hi I'm having trouble linking a program that uses boost::call_once() on a Windows AMD64 machine. I get a link error saying _InterlockedCompareExchange() is undefined - this should be an intrinsic function on this platform but I think the code in thread/src/once.cpp where the address is taken of the intrinsic function has fooled the development system. It works OK on IA64 were the function is also intrinsic. We are building statically so it's possible that we are not passing some compiler switch that fixes this - but I don't see it. Has anyone else hit this problem with 64-bit AMD64 code and boost::call_once() on Windows? Compiler version is: Microsoft (R) C/C++ Optimizing Compiler Version 14.00.40121 for AMD64 Bill Somerville