[boost] [optional]none.hpp causes VC7.1 precompiled header to behave erratically

It looks like VC7.1 doest not handle boost::none properly when it is included in a precompiled header. I started getting all sorts of weird errors after including boost/none.hpp in one of my precompiled headers. There is a comment in the file that warns borland users about the problem and it seems VC has a similar issue (I only tested it on VC7.1). Interestingly, I notice that boost::none is defined in an unnamed namespace. Since boost::none is const and thus has internal linkage so I removed the unnamed namespace and everything started working again. So my questions is what purpose the unnamed namespace serves? Can it be removed in light of this problem with precompiled headers? Thanks, Sean