Windows 7 goes into sleep mode after a certain time of inactivity when the Windows 7 power saving feature is enabled. This disconnects the network and causes the VMware Tools and the virtual machines to stop responding.

To resolve this issue, set the power saving feature, ensuring the virtual machine is always powered on.
To change the power settings, ensuring the virtual machine is always powered on:
  1. Navigate to Control Panel > Hardware & Sound > Power Options.
  2. Under Additional Power Plans, click High Performance.
  3. Click Change Plan Settings.
  4. Set all settings to Never.
  5. Click Save.