OK, found it.
Go to regedit,
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sermouse
Find entry "Start", set value to HEX 3 (manual) or 4 (disabled). Restart.
OK, found it.
Go to regedit,
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sermouse
Find entry "Start", set value to HEX 3 (manual) or 4 (disabled). Restart.