Some cod 4 PC problems~?

1) i just recently patched to 1.5 and was excited for winter crash, unfortunately, for some reason, every time i try to access the map the game crashes(even when i create a server with the map on) i think its corrupt but i dunno where to get the map itself only

2)i keep getting connection interrupted... its really annoying... is it because im on wireless? and can i do anything about it? and i cant really use a cable(if i can trust me i would) since im here in my room (2nd floor) and the router is at the basement =s....