boost::thread and MinGW

Hi, I was previously using the threading library with MinGW (latest release version) with no problems. Yesterday I came across a segfault that occurred when accessing a shared pointer so I updated the boost-cvs version I was using to see if it was a known problem that had been fixed; however when attempting to build the new version it appeared that threading had been disabled for MinGW? Is this the case or is it a problem with the way I'm building my code. Any help greatly appreciated, Russ