id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host 12744,Error 0x000000C4 when booting Windows 7 x64 (Ubuntu 12.04 x64 host) after update to 4.3.8-92456 [FIXED in SVN],uchuujin,,"Hello! I just encountered the following error: - Host OS: Ubuntu 12.04 x64 - Updated Virtualbox 4.3.6-91406 to 4.3.8-92456 from the official Virtualbox repository - Updated the guest additions too - Started Windows 7 x64 virtual machine (was running fine before) - The machine crashed with error STOP: 0x000000C4 upon startup After that, I tried the following: - the solution suggested in https://www.virtualbox.org/ticket/11841 (VBoxManage setextradata [vmname] VBoxInternal/CPUM/CMPXCHG16B 1) - Downgrading guest additions to 4.3.6-91406 - Removing guest aditions altogether - Turning off hardware acceleration (graphics, CPU) None of this works. My virtual machine crashes everytime, so I cannot use it anymore. Please find a capture of the error message and Vbox.log attached.",defect,closed,other,VirtualBox 4.3.8,fixed,,,Windows,Linux