If you read The August Patches to Avoid for Now, you know that there are various issues related to Microsoft's update releases for this month. The biggest issue is that KB2976897, KB2982791, and KB2970228 are reported to cause bluescreens on boot in some situations. Watching the community communications over the past few days, it's become clear that not everyone is affected. What we know so far is that the bluescreen problems can happen on Windows 7 64bit systems, and that the actual bluescreen error code is: win32k.sys PAGE_FAULT_IN_NONPAGED_AREA Error Code 0x50
But, really, it doesn’t matter what else we discover, it's important for those experiencing problems to be able to solve the problem to allow computers to boot successfully.
Community member rvuerinckx posted a solution in the Microsoft forums yesterday that seems to indicate that the problem stems from a corrupted FNTCACHE.DAT file.
The solution is to boot to DVD (or some other alternate booting mechanism), and remove the FNTCACHE.DAT file, which is located in the C:\Windows\System32 directory.