cant join games in progress and other woes

[taliosfalcon]

If i'm in a game before it starts i have no problem, however when i try to join a game in progress it gets to around 25% transferring data to my harddrive or whatever then freezes for 5 mintues before telling me i lost the connection to the host. I've tried completely removing my firewall to no effect and i'm not behind a router. i've also tried uninstalling civ4, removing all the leftover files and reinstalling. The game also completely freezes my computer requring a hard reboot whenever i try to retire or quit to the main menu from a multiplayer game, this does not happen in single player.
any help would be greatly appreciated
Specs-
p4 3.4 extreme edition
2 gigs ddr2 533 ram
radeon x800xl
cable connection