Wakenaam, Go to the link below and click the "?" to the left of "Why don't my Notification Area icons show or why do they disappear?" to expand it and you'll find several possible fixes.
Friends: Of recent I have noticed my speaker icon in the taskbar disappeared. I unchecked then re-checked the icon in Control Panel and it reappeared. However, when I rebooted the icon was gone again. I spent hours trying different solutions on the net, but nothing seems to work. Has anyone had a similar problem who can offer a working solution? Thanks for any help. Windows XP Pro SP2. Compaq Evo