I just upgraded from X11R6 to X11R7 (7.1). I also removed my fontconfig package with pkgtool (Slackware 11 is my distro), and downloaded the latest fontconfig-2.4 to install. Strangely, "configure" and "make" run perfectly, but "make install" fails after a bit. When I run "make install" (with root privileges, of course) it stops at an error saying something about "./fontconfig-devel" not found (or something like that).
I'll post the actual error message sometime soon, but I am not using linux now, because X only shows boxes instead of letters....
Please help me figure out what this problem is.

You didn't install the development package in fontconfig? fontconfig-devel is not in your path?

Always make a note of the exact error message when it occurs.