What should you do first:
- If you're having problems downloading your game, consult this support article
- Be sure to check the support article section related to the game you're having problems with. There you can also find troubleshooting threads which our users have found helpful.
- It's important that you have the latest version of DirectX and graphics drivers installed!
- If you're using Windows Vista or 7, you should try disabling UAC. More information can be found here
- Installing the latest updates for your operating system is always a good idea and can also resolve some of your issues. Same thing goes for shutting down or disabling any non-crucial applications running in the background, especially anti-virus software, as they might interfere with your games. Try it and see if it helps.