Disappearing icons in systray.

I am having an issue in NT4.0 where the icons in the system tray disappear after I log off and then back on. If I reboot the computer or restart, I don’t have the issue. It only happens when logging off. I tried reinstalling the service pack(SP5), but am still having the same problem. I have not been able to find anything on Technet regarding perhaps a corrupt systray.exe. If anyone has experienced this same problem, I would love to hear from you. Thanks.