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.
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 can often times be caused by closing the downloader early.