1. Make sure that you have DirectX 9, if you are using Windows Vista or 7 then update the DirectX to 11.
2. Make sure you're up to date (that you have your mu updated with your MU Updater).
3. Make sure that none of your programs are using.
4. Turn off your firewalls.
Other options -> Since main.exe crashes some process auto injects to main.exe while you are trying to connect try to clean it with NOD32 or Kaspersky Pure.