MVDM Question

[First time poster long time listener]

I'm using MVDM, and so have four "desktops" on my
monitor. I love the program, but there is one thing that
kills me: most times, with an IE window open on #3 or #4,
if I go to screen #1 or #2, the windows close and are gone
when I return to screen #3. Any idea what causes this
behavior in an otherwise delightful Powertoy?

Thanks