[Boost-users] assignment operator could not be generated

When building a project that uses boost on Windows under MSVC 9.0 (VS 2008), I get _tons_ of warnings for "assignment operator could not be generated" all throughout the code. Is this going to cause subtle errors when I run the code, or are the warnings harmless ones that can be disabled with pragmas? One example where I get lots of "assignment operator could not be generated" spam is in boost::detail::addr_impl_ref<T> when I try to use boost::bind. But there are many other places as well. I can produce an explicit sample if requested, but since it happens so frequently and I haven't done anything special AFAIK to make it happen, I suspect someone else will immediately know what I'm talking about.