i had the problem that the game crashed at start with the message "UDK.exe stopped working"…
All the guides in the forums didn't help, so i took a look into it on my own. I looked into the log files located at C:\Users\*Username*\Documents\My Games\Chivalry Medieval Warfare\UDKGame\Logs and i found out that the critical errors are a result of failing comparisons of the UDK ini files with their hashes. http://pastebin.com/4a6aUQvN
I've deleted the named ini files located at D:\Program Files\Steam\steamapps\common\chivalrymedievalwarfare\UDKGame\Config and started the game again. It installed the redistributable stuff again and crashed as usual… but now the log files name other ini files as corrupt − what the hell…?
So i've deleted all the ini files located in this directory: D:\Program Files\Steam\steamapps\common\chivalrymedievalwarfare\UDKGame\Config
Afterwards, i verified the game data with steam and it downloaded the deleted files as assumed. Then a click on the Play button: it worked... the game finally starts… O_O
Maybe this will work for you. I assume that there are some problems downloading the files correctly? You may have to try this a few times… let me know if that worked for your or not :-)