Ian,
If those windows open small (but they ARE visible) then stretch one of them
out to the desired size- don't use maximize.
Close other IE windows. Close that window last.
If they open minimized to the taskbar, try this:
When you right-click the button on the taskbar, there are options for "size"
and "move" right? Experiment with Size first, using the arrow keys on the
keyboard. Then try the Move option with the arrow keys. Your window is
probably very small and off the screen or very, very small (1 pixel?) but
still on the screen. Once you can see it, drag it out to the desired size
and make it the last IE window you close.
Regards,
Don