Dê uma olhada no KB da Microsoft sobre o assunto :
When you start a computer that is running Windows Vista or Windows 7 for the first time, one or more of the following icons do not appear in the notification area in the lower-right corner of the screen.
- The Network icon
- The Volume icon
- The Power icon
You may also notice that the check boxes for the related system icons are not selected on the Notification Area tab of the Taskbar and Start Menu Properties dialog box. However, the network, volume, and power features function correctly even though their associated icons do not appear in the notification area. You can access these features by using Control Panel.
If you gave your computer enough time to finish the startup service initializations before you restarted it, and one or more of the system icons still do not appear in the notification area after the restart, you can make them reappear by deleting two subkeys from the registry.
A Microsoft fornece um arquivo "Fix It For Me" que fará automaticamente as alterações necessárias para corrigir esse problema. Você pode fazer o download da solução Fix It For Me ou seguir estas etapas para corrigir você mesmo:
Click Start, type
regedit
in the Start Search box, and then press ENTER. If you are prompted for an administrator password or for confirmation, type the password, or click Allow.Locate and then click the following registry subkey:
HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify
In the Details pane, click the
IconStreams
registry entry.On the Edit menu, click Delete, and then click Yes.
In the Details pane, click the
PastIconsStream
registry entry.On the Edit menu, click Delete, and then click Yes.
Exit Registry Editor.
Either restart the computer or the
Explorer.exe
process.*
* A maneira mais fácil de reiniciar explorer
é clicar no menu Iniciar, pressionar Ctrl + Deslocar e clicar com o botão direito do mouse na área vazia do menu Iniciar e selecione "Sair do Explorer".
Em seguida, pressione Ctrl + Desloc + Esc , clique em Arquivo - > Novas Tarefas (Executar) e digite explorer
e clique em OK. Feche o Gerenciador de Tarefas quando terminar.