AMD has issued a hotfix for th

After installing ATI Catalyst driver release 8.12 for two or more ATI Radeon HD 4850 graphics cards in a system with ATI CrossFireX technology, the system restarted and halted on a black screen. The black screen occured prior to the loading of the desktop for the Windows Vista 64-bit or Windows Vista 32-bit operating systems, according to AMD.

This issue only occurs when two or more ATI Radeon HD 4850 graphic cards are installed in the system with ATI CrossFireX technology.

AMD recommends the installation of the following hotfix that may help resolve the issue:

Catalyst 8.12 Hotfix for Windows Vista 32-bit Edition
Catalyst 8.12 Hotfix for Windows Vista 64-bit Edition

Note: The hotfix driver is only necessary if two or more ATI Radeon HD 4850 graphic cards are installed in the system with ATI CrossFireX technology