Tray Icon disapers

[Fazi]

Hai friends.

My programs loads to system tray at windows startup.

After loading xp, on few occations the icon is not shown in tray. but i can see the program running in Task Manager.

With icodata
.cbSize = Len(icodata)
.hwnd = Me.hwnd
.hIcon = Me.Icon
.szTip = "My program name and version" & Chr$(0) '0 is for truncate
.ucallbackMessage = WM_LBUTTONDOWN
.uFlags = NIF_ICON Or NIF_TIP Or NIF_MESSAGE
.uId = 1
End With
Shell_NotifyIcon NIM_ADD, icodata

Any thing wrong with the codes?
if not what could be the problem you think?

It is remarkable that i have not add any flags to the oprograms startup entry path. i.e. -osboot , /STARTUP , -quiet