Claude Desktop on Windows 11 unconditionally launches a Hyper-V virtual machine consuming approximately 1.8 GB of RAM every time the app starts, even when users only need chat functionality. The VM process (Vmmem) appears in Task Manager with no CPU usage but significant memory overhead, representing over 11% of a 16 GB system's total memory before any actual work begins.

Investigation reveals the Hyper-V Host Compute Service spawns vmwp.exe via an RPC interface event, despite VirtualMachinePlatform being the only enabled virtualization feature. The user discovered 2,689 stale session files accumulated in the local-agent-mode-sessions directory, following Docker-style naming conventions. PowerShell diagnostics confirm WSL, Docker, and other virtualization tools are disabled, yet the vmcompute service triggers automatically on app launch.

On a 16 GB laptop, this bug pushes memory usage from 50% to 62% at idle, causing system sluggishness and forcing manual process termination after every launch. The Hyper-V Compute Admin log shows repeated JSON validation errors: "The specified property query is invalid: The virtual machine or container JSON document is invalid. (0xC037010D)" dating back to February 19.

The workaround requires disabling VirtualMachinePlatform entirely, which prevents the VM spawn but eliminates Cowork functionality. Users request on-demand VM initialization only when agent mode is active, automatic cleanup of stale session files, and graceful fallback to chat-only mode when VM infrastructure fails.