The Computer Maintenance service in Windows 7 sometimes has a tendency to automatically remove desktop shortcuts to network locations, which can be really annoying. You can turn off this service locally or via GPO to prevent the shortcuts from being removed automatically.
Through Control Panel → Troubleshooting. On the left, select Change Settings, then choose to disable Computer Maintenance.
The policy setting is located at Computer Configuration\Administrative Templates\system\Troubleshooting and Diagnostics\Scheduled maintenance. Set the policy setting Configure Scheduled Maintenance Behavior to disabled.