I'd recommend restarting the downloader to see if you can pick that up.
When restarting the downloader, make sure to select the same download folder that you did before.
This issue affects users of ATI Radeon HD 2400, 2600, 2900, 3400, 36 graphics cards under Windows Vista and Windows 7.
ATI Radeon HD 4600, 4700, 4800, 5000, 60 series products are unaffected, as is Windows XP.
Most of these can be solved by commonsense troubleshooting techniques, but some others are a bit more .
We'll keep this post updated throughout the next couple of days with the latest problems and info on how to fix them.
If you've pre-downloaded the digital version of the game in these languages before AM CEST ( AM GMT) on Saturday May 12, you must obtain the new downloaders to be able to install properly once the game is released on May 15.
Update: ATI has released a Catalyst 12.4a driver hotfix for the affected cards.
Please check this link for more information: the Beta, several startup issues were resolved by setting the Diablo III tools to run in Compatibility Mode.
At this time, Compatibility Mode for the retail tools is no longer needed.
In fact, setting the tools to run in Compatibility Mode may cause other issues with the Blizzard Launcher.
If you participated in the Diablo III beta, we recommend removing all Installation Files before attempting to install the retail client.