iaschick

Whenever I click on any server to play the DayZ Mod, it gives me a connection, then a box that says "Files..(C:\Program Files)..are not signed by a key accepted by this server. To play on this server, remove listed files or install additional accepted keys." and then disconnects and doesn't allow me to enter any server. Now I am very new to this game and am a tad bit confused on how to approach this. If someone could help me I would greatly appreciate it, for I have no idea what this means. Thanks