Hi I have the same problem , I can't see the techs in the tech tree.
( I opened steam in administrator mode, yes, I have vista.) I tried verifying the game cache. A file is missing, so it says that the file will be downloaded. But again, same problem.
- I previously installed mods but i uninstalled the game after that and i cleaned my whole PC using ccleaner and I deleted all civ related files. Then again same problem.
-My problem came with the update
-I also tried to change languages and put it back but still same ****
Right now I feel like this civ got me pinned down. Thanx for suggestions.