The Tech Report writes users of Radeon HD 3800 and Radeon HD 4800 series graphics cards in CrossFire are having BSOD problems with the Catalyst 8.11 driver on Windows Vista x64:
Judging from the posts, two ingredients are required to reproduce the issue: a 64-bit version of Windows Vista and a CrossFire setup with dual Radeon HD 3800- or 4800-series GPUs. Many affected users say they're using Intel motherboards with 3- and 4-series chipsets, but at least one has complained of the same startup BSODs on an AMD-based system. This phenomenon isn't restricted to AMD forum dwellers, either—we've spotted similar complaints in this Rage3D forum thread.
Some users have proposed workarounds involving new Intel chipset drivers and using third-party tools to remove the drivers before installing an older release and finally loading up the 8.11 version, but those suggestions don't seem to help everyone. Meanwhile, those who contacted AMD tech support apparently weren't any luckier.