Out-of-date drivers and operating systems can cause a variety of issues, and are one of the first things to check when a game is having problems.
Troubleshooting steps for disconnection issues when playing Diablo III.
Troubleshooting steps for latency problems in Diablo III
Troubleshooting steps for connection problems
What to do if you can't claim a beta key for a Blizzard game.
How to obtain error logs for Blizzard games
Information on what to do when a game update is stuck at 0 B/Ss
Troubleshooting steps for performance-related problems.
Follow these steps to troubleshoot problems with your low-speed or wireless internet connection.
Information on moving Blizzard games to a different hard drive