Cant launch cf

I have this problem that started occurring recently , used to open CF and login and play easily before but as from today , when ever i open CF the log-in screen appears for 1 sec then it closes and i can't log into CF or play , as soon as i Press "start" the log in screen appears and closes at the same time , i re-downloaded CF and i re-installed it , didn't download any other programs or antiviruses on my computer .... can some1 help me plz regarding this ? i got Windows XP with SP 2