1. Make sure you have the latest version of Java: https://www.java.com/verify
2. Clear Java cache: Java Control Panel -> General -> Settings -> Delete Files
3. Make sure (outgoing) ports 80, 443 and 10443 are not blocked on your firewall and/or router.
To login first go to - control panel of your pc - java control panel - settings - delete files - tick ( trace and log files , cached applications and applets) and then retry to log in. If problem is not solved type "unable to launch " in community Q&A .