1) Update video card drivers
. The newest driver
always have fixes to certain games with certain configurations. Make sure to always keep the drivers up-to-date.
2) Uninstall then reinstall the game. Chances are if the gameis failing to load half the time, a few of the files were corrupted during the install.
As far as the mutiplayer issue, I'm not sure. If it is saying to are banned, contact the support desk. Your serial for the game may have been stolen... assuming this is a legit copy that you got.