This won't be a response to your exact problem but I hope it at least gives you some confidence the problem is fixable/re-treadable.
Note: The very first Kursk mission release did the same thing to me!
Question is are you 100% certain you have the Kursk Pre Alpha mission1 version 6 and not the first??.
I only say this as we have a lot of releases and its easy to "drag and drop" a file when the title is abbreviated and you can't sometimes see the whole thing unless you look at properties. I nearly installed the wrong release once - two folders side by side and I grabbed the wrong one!!
I checked before unpacking etc and it was obvious.
Probably not an issue for you as I am a Dork and sometimes behave Dorkily.
If not maybe once more start from scratch again!!??? rebooting each time. I resolved a graphics problem (came from nowhere) by reintalling everything again. Now I move the whole content of each "upgrade" to an entirely different folder (i.e. I have basic TvsT, then the TvsT plus Pre Kursk Av.1 and finally TvsT plus Pre-KurskAv.1 and KurkPreAv.6). All tested as I add the releases. Any problems can be resolved by nuking the 'naughty' file and copying the contents over (in the case of a glitch such as you describe).
I am very conscious that I haven't really helped you mate but I'm sure you'll get there; sometimes it takes some real pain though
Interested to hear how you get on
All the Best - Mort
