I am having the same problem. At login, I lock up and have to reboot computer. I run zonealarm firewall, Yahoo IM, Mcafee anit-virus, UD Agent, plus standard windows background programs. My hardware: Intel II P4 2.4 ghz, 512 mbs of RAM, Radeon 9600 256 mb, DSL connection thru linksys Router.
This is the same setup I run COH with and I dont have any problems there.