First of all welcome to the forum.
It sounds like your install is messed up. Part of the problem appears to be that you mention that you've installed RTR 6 Gold and also mention platinum 1.9 - these are actually two different mods.
Best thing is to start again - uninstall RTW and then install again.
As you have RTW 1.5 there is no way that you can use RTR 6 Gold as that only works with RTW 1.2. You just need RTR PE.
When you install the mod make sure that you point the install at the RTW game folder and not the data folder (basically this is the folder where the exes are held). Also make sure that the installer is pointed to the cirrect folder - sometimes the default path may not be the correct one (some problems are caused by early versions of RTW had 'Actrivision' as part of the path and later versions have 'The Creative Assembly').
The other thing to do is to add the -show_err switch to the shortcut properties. How to do this is described in this thread:
http://www.twcenter.net/forums/showthread.php?t=62217
The idea of the -show_err switch is that if there is an error trapped as part of the CTD you will see the error message - not all CTDs have an error message.
One more thing you may want to consider is that when you have a fully patched and working RTW is to take a copy of that folder and apply any mods to the copy of the folder. This way you will never have to uninstall/reinstall again - unless you change PCs. How to do this is also mentioned in the thread I've included the link to.
There is no limit to how many copies of the RTW, the following is an examples of what I used to have on one system (as you can see this install was an old one with Activision as part of the path name):