This can be a common problem on windows XP. There are many registry hacks ect. to try and solve the issue, but i have always found it to be software/driver problems. One known culprit can be Nero. However, in my experience, the volume icon is the cause of the problem. if you go to control panel/sounds and un-check the "place volume icon in taskbar" and apply, some missing icons can re-appear. If you the re-check the "place volume icon in taskbar" the volume icon will return also.
Its as if the volume icon causes a bottleneck, causing all subsequent icons to become non visable.
I have had this on a few installs, and the workaround seems similar regardless.
Example: SB Live sound card.
On a fresh XP install, windows has basic drivers for this card, so no need for the Creative bloat. However, this can cause the taskbar icon problem. Simply go into task manager, and un-install the card. Re-boot. Windows will re install the card automatically and the problem should be gone.
If you install the creative software however, the icon problem never seems to occur.
Example: On board sound
Simply update the drivers for the MB. This essentially un-installs then re-installs the card, again solving the issue.
The common thing seems to be that the windows sound card drivers cause this issue during installation, or when certain programs are installed. its as if the sound card driver needs re-setting. There are far more knowledgeble people on here that may be able to give a reason for this. I was just happy i figured it out.
Its always the small problems that are the most annoying.
Good Luck
