Blizzard wants to remind the some 2 million gamers that participated in both the closed and open beta stress test weekend that you need to totally uninstall the beta including the Battle.net folders before you installing the full version of Diablo 3.
If you have installed the Diablo III beta at any point and intend to install Diablo III, please make sure that all Diablo III beta files are removed from your system prior to installing the full game.
This includes the Battle.net folder, which can be found in the following locations:
C:\Documents and Settings\All Users\Application Data\Battle.net
Once this folder and all other beta files are removed, simply run the installer again.
Also if you have an ATI graphics card you might want to check this out.
We’ve recently become aware that playing Diablo III with the latest Catalyst 12.4 drivers for ATI cards may cause some visual artifacts for specific hardware configurations. This issue affects users of ATI Radeon HD 2400, 2600, 2900, 3400, 3600 and 4500 graphics cards under Windows Vista and Windows 7. ATI Radeon HD 4600, 4700, 4800, 5000, 6000 and 7000 series products are unaffected, as is Windows XP.
ATI is aware and investigating. Until a solution can be provided we recommend those affected use the Catalyst 12.3 drivers.
This issue has now been resolved in the AMD Catalyst 12.4a hotfix driver. Users of the ATI Radeon HD 2400, 2600, 2900, 3400, 3600 and 4500 graphics cards are the only AMD customers who need to download this hotfix driver.