Well if you don't have mods at the moment did you had mods before installing TTW? Some mods leave stuff behind or change things (like files and settings, etc) that might still affect the game even if they are not in use anymore. Also validating the files through Steam will not reinstall the game it usually doesn't even take more than a couple of minutes if there is no file to be replaced, if there are any files than it will need to download them and that takes a bit longer depending on the internet speed but still it's advisable if there are any that were changed or are corrupt.
Also I do understand not wanting to reinstall the game(s) and TTW again, it does take ages to do it all specially if you don't have a hard copy of the games and have to download them each time you want to install, but sometimes that is the only option that will work (I know because in one month I had to install both games around 5 times and TTW over 10 times) my advice if you will do it in the future, after uninstalling the game delete it's folder on steam and on your "my games" one in your documents before installing the game again, that way you will have a real unaltered game installation, then you should copy the game folder from steam and put it somewhere else for safe keeping, that way next time you need to install the game all you have to do is after uninstalling it and deleting the folders again, copy your backup (or safe keeping as I called it before
) folder and put it back in the steam games one and no more need to go through the installation process again.
Sorry about the wall of text and about not giving a real answer for the problem, and I am not trying to sound like I am a grumpy old guy or something, it's just some information to leave around here
.