Try to use FORloop instead of FOR EACH.

oShell = CREATEOBJ('Shell.Application')
oIEColl = oShell.Windows
FOR i = oIEColl.Count-1 TO 0 STEP -1
	oInstance = oIEColl.Item(i)
	oInstance.Quit
ENDFOR
oIEColl = NULL
oShell = NULL

>this code is good but it doesn't close IE 5.5 or later windows. why ?
>
>oShell = CREATEOBJ('Shell.Application')
>oIEColl = oShell.Windows
>FOR EACH oInstance in oIEColl
> oInstance.Quit
>ENDFOR
>oIEColl = NULL
>oShell = NULL