Yes I've re-installed the game several times. I just tried a completely fresh install just then with the re-downloaded versions of the mods plus deleted the graphics cash. Same problem occurs. I'm starting to run out of things to try haha. As far as saved vs. new games I've only been doing it with new games. I'm running this on a brand new PC so I don't actually have any save files on here as of yet.
Update: Ok so after I had re-installed the games & mods and found the problem was still occuring, I deactivated and uninstalled the mods via TFmm and manually deleted any remaining files. Since I've done this the icons for all the industry buildings, signals and stations aren't displaying properly in game. Worst part is though, even with the mods removed, the game is still freezing. I have verified the game cache via steam. It seems the only way to get it back to a stable state once the problem occurs is to totally remove the game and re-install it. Something weird is definitely going on here. I wondered if perhaps cost_mod has some compatibility issues with the new version of TF, but surely if that were the case more people would be having this problem.