mrsparky: Problem solved - I just made another zip file of the Control Tower and uploaded it to CGShare. This time it shows on their system as a .zip file. I downloaded, opened it and checked the unzipped files and everthing looks to be ok.

If renaming your .sit to .zip doesn't work then I can only suggest redownloading. If you still have problems after that I will place the zip file in my file locker here at Renderosity for you to download.