Blank Screen When Resuming with MS-DOS Prompt Active (260712)

CAUSE

The resume operation involves a complex sequence of interactions between the currently active Virtual Machine (VM) and the following virtual devices: keyboard (VKD), mouse (VMOUSE), power (VPOWERD), and Configuration Manager (CONFIGMGR). The system broadcasts power-status messages to the installed drivers and running programs, and also initiates follow-up actions that wake up the user interface within the context of the active program. One of the critical items in this sequence is the necessity for full internal status and event checks of the system message queue, which occur as a natural consequence of normal window message processing by a program. This event sequencing stops because of the nature of the MS-DOS prompt.

The MS-DOS prompt runs within its own virtual machine (VM), which is separate from the system VM in which the visible window runs. This visible window is embodied in Winoldap.exe, which is a 32-bit Windows-based program with some specialized features that allow it to manage the interface for MS-DOS-based programs (such as the command prompt). It must reroute keyboard input directly to the client program VM. This means that Winoldap does not receive standard WM_KEYUP and WM_KEYDOWN messages, which is why the resume sequence stops. However, it does receive and handle the remaining assortment of window messages, including WM_MOUSEMOVE, WM_SYSKEYUP, WM_SYSKEYDOWN, and so on, which is why moving the mouse or pressing a Windows shortcut key combination causes the system to completely wake up. This also accounts for the fact that all other keyboard activity initiated between the initiation and completion of the resume process is directed to the MS-DOS-based program.