Clear Past Icons from the Tray Notification Area (Windows XP)
This tweak allows you to clear the Past Items list in the customized notifications area of the systray.
Open your registry and find the key below.
To clear the notification history delete the values called "IconStreams" and "PastIconsStream".
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.
Disclaimer: Modifying the registry can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from modifications to the registry can be solved. Use the information provided at your own risk.