Volume taskbar icon

Hello.

I'm having a problem with the volume icon in the taskbar. When I reboot my
computer, the icon disappears.

I have read the articles below:

http://support.microsoft.com/default...b;en-us;245692

http://support.microsoft.com/default...b;en-us;319095

and followed the instructions but no success.

One thing to note is that when I log off my account and log on back the icon
appears.

There is no exclamation mark next to the sound driver in device manager. So
it means the sound driver loaded successfully.

I think maybe there is some conflict with drivers... I don't know...

Any one can help me???

Details:
Windows XP Pro SP2