Thanks. You were correct in that it seemed to be a gcc problem, I tried intalling earlier versions. Non of the 1.4.x versions worked, but once I whent back to 1.3.x things wrked much better.
I'm trying to install LyX 1.4.3 on a machine running Redhat 7.3. I can't upgrade the OS since I don't have root, but I've been given permission to install sw into pkgs by the Sys Admins....