Hi Bert, Building on RHEL 3 and 4, give the following error, RHEL 5 builds ok. CXXFLAGS=-I/temp/boost_1_39_0 ./configure Testing dependencies and compiler. Using gmake to build Makefile:45: Extraneous text after `else' directive Makefile:48: *** only one `else' per conditional. Stop. Regards, Bas