Solus, I have the same problem.
I play TAD in two computers, my parentes is a 15" screen and the far zoom is great. My computer is more powerfull and the screen is 19" LCD. And, unbelievable, the far zoom isn't so... far.
When I start the Japanese Campain, for instance, the zoom are closet at 2 guys, so, when it zoom out everything are still big and my options is already seted "very far".
I tried you strategy of deleting the folder, no way, the zoom was the same.
Downloaded the latest video drive (geforce 7600GT)... nothing.
And more, I tried WTC , its zoom was good before instal TAD, now is the same.
Before posting, I looked for the same doubt but they didn't say how they got it, if they did.
Someone know how do I solve it? I will go to my parents house just in tow weeks and want to play TAD NOW! =)