i downloaded it from insecure.org, so i know where i downloaded it from was all kooshty, and yes i've got winPcap, got it it when i downloaded cain.
But not to worry though, uninstalled it then re-installed it about three times, them i tried v4.53 and it's all working fine now.
p.s i've got a personal question for you, on one of your posts i read that you were once a penetration tester. This is what i want to do. My question to you is were there any particular qualifications you needed for that job?