AMD has released a Catalyst driver hotfix for a so-called "gray screen" problem affecting Radeon HD 5800 users. The hotfix is available from AMD's support knowledge base as two downloads: one for Windows 7 and Vista and another for Windows XP, all in either 32-bit or 64-bit variants. Both downloads appear to concern only Radeon HD 5800 graphics cards.
The knowledge base entry describes the hotfix as follows:
Alleviates some of the intermittent grey screen and vertical line corruptions that may randomly appear during normal usage when using an ATI™ Radeon HD 5800 series graphics card
A search for complaints about the problem reveals this thread on AMD's Game forums, where users have been detailing the issue (and providing screenshots) since late November 2009. In another thread, one forum member quotes AMD's support staff as saying the problem had to do with a Windows 7 update, and AMD was "looking at it" as of December 30. The company wasn't able to get a fix in the Catalyst 10.1 release that came out last week, though.