1) Does RTW 1.0 load, or is it strictly a problem with v1.2?

2) Do you have MSS32.DLL? It should be right there in your RTW main folder. If not, do a search for that file name and see if it's being installed someplace else. Sometimes people move the game directory (or use a copy), and RTW will install the patch where it THINKS the game should be, not where it is.