Ok, try copying the original file sndvol32.exe across from Windows\Sysstem32\DLLCache to Windows\Sysstem32 - then go back to your sound settings in Control Panel, place the check mark against "place volume icon in taskbar...." - reboot and test.
From Kellys-Korner;
Volume Control - The volume icon does not appear in the notification area (system tray) Go to Start/Control Panel/Sounds and Audio Devices. On the Volume Tab under Device Volume, put a check in the box that reads: Place volume icon in the taskbar.
If that has been tried:
Place your XP CD in then go to Start/Run and type in:
EXPAND -R X:\I386\powrprof.dl_ C:\Windows\System32
Once done: Go to Start/Run and type in: regsvr32 stobject.dll
Other Checkpoints:
Make sure Hide Inactive is disabled in Taskbar Properties. In Sound and Audio Devices Properties, make sure "Place volume icon in the taskbar" is checked. If it still doesn't work, here are two workarounds:
- Go to Start/Log off (log off then log back on).
- Right-click the taskbar & select Task Manager under Processes tab select Explorer.Exe & End Task. Under Applications tab select New Task, type in "explorer" and click OK.