Hello everyone! I'm the developer of AutoTileGen. The current version of autotilegen fixes all those problems (you can now select a drive letter) and a lot of other bugs.
It will be made available on Steam today.
Here is a video showing it's current state (it seems I can't post URLs... just remove the spaces): www . youtube . com /watch?v=b0GCIBrYHpQ
I hope you like it! I'll be around in case you have any more issues with the application