Windows 11's January update, KB5074109, has caused a bug affecting sleep mode on certain older PCs, leading to system crashes that require hard reboots. Users have reported that the issue appears only when the update is installed and resolves upon its removal. This problem primarily affects older machines using the S3 sleep state, while newer devices with modern standby features are less impacted. A suggested workaround involves unplugging USB webcams. Additional issues reported include freezing with the Outlook app for POP accounts, shutdown failures for enterprise users, and problems with keyboard and mouse functionality. Microsoft has acknowledged some of these issues and has deployed emergency fixes for certain problems.