New Taskbar Repair Tool Plus! Notification Area and more. Download here.

Chevron is missing: For some users, setting the very first icon to Always Hide, restores the arrow/chevron. Note: It does time time for it to become effective.  Hide Inactive Icons is Greyed Out - Run this edit to restore.

Icons are missing or disappear, reappear:

This happens for most Auto-Logon users. Methods/workarounds: Log off and Log back on, password protect your account or disable SSDP and uPNP Services.

Disable SSDP and uPNP Services (Line 156)
http://www.kellys-korner-xp.com/xp_tweaks.htm

Or if you are running XP SP1 uninstall UPnP from Add/Remove Windows Components.

Hide or Show Inactive Icons in the Notification Area (Line 53)
http://www.kellys-korner-xp.com/xp_tweaks.htm

Remove Past Items From the Notification Area (Line 53)
http://www.kellys-korner-xp.com/xp_tweaks.htm

Once done, Open Task Manager, click the Processes tab, click Explorer.exe, and then click End Process. In Task Manager, click File, click New Task, type explorer, and then click OK.

Volume Control disappears: Save Settings on Exit (Line 54)
http://www.kellys-korner-xp.com/xp_tweaks.htm
Restore Volume Control and Net Icon to the Notification Area (Line 320)
http://www.kellys-korner-xp.com/xp_tweaks.htm

To use the Regedits: Save the REG File to your hard disk. Double click it and answer yes to the import prompt. REG files can be viewed in Notepad by right clicking on the file and selecting Edit.

Icons in the Notification Area May Disappear If You Use High-Contrast Color Themes in Windows XP http://support.microsoft.com/default.aspx?scid=KB;en-us;q321213

Troubleshooting the Notification Area
http://www.kellys-korner-xp.com/xp_n.htm#na

Troubleshooting the Volume Control Icon
http://www.kellys-korner-xp.com/xp_v.htm#volume

Hide All Notification Area Icons (Line 134)
http://www.kellys-korner-xp.com/xp_tweaks.htm