I had a similar problem. Dont write it in stone, but as far as I was able to figure out, the problem is that you installed 1.3 over 1.2 but it remained labelled "1.2 " in the registry (I saw a registry tag of 1.2 when I went looking). In frustration, I uninstalled everything RTW and BI and played MTW for a while. Just last week I did a fresh install of RTW (1.0 -> 1.2 -> 1.5) with no problems then RTR overtop and everything went smoothly.