login screen freeze up or crash ?

i have played cf before but not for a wile an i just downloaded it an installed it on my Dell

Vista Desktop it has over the reqments an i have messed with the settings like run as

admin an compat with xp ect.. an tryed all the solutions suggested like reinstall an turn off

your firewall ect.. an nothen seems to work it just freezes on the login screen but you still

hear the music or crashes on login screen when i click on it an all i can do is ctrl, alt,

delete an end task an it says not responding. but everything seems to be working till the

login screen comes up !? i have tryed everything i can think of. an this is my only PC. so i

dont know how to fix it plz help ?