Progress Bar Keeps Running When Replacing A Frame

I've the following problem. I have a webpage with some frames on it.
In one frame i have two buttons "reports" and "Analyis". When Someone
pushes reports, a frame must be replaced next to the menu. When the
first time a button is pushed, the frame next to the buttons is
replaced but the progress bar in explorer keeps on going...keh?.. The
second time i push the button the frame is loaded but no progress bar
(??).. The third time again a progress bar.. the fourth time not..so
it seems that it's happening every oneven action.

I've IE 6. I looked in the KB of microsoft and find something about it
but only for IE 5.5 (should be solved by now).

So this is the code:

if (grp=="Reports"){
//window.open("displayReport.csp?type=2")
top.listframe.location.replace("displayReport.csp?type=2");
}
else if (grp=="Dashboards") {
top.listframe.location.replace("displayReport.csp?type=275");
}

I've commented window.open("displayReport.csp?type=2"). When i
uncomment this no progress bar is shown so my conclusion so far is
that it has something to do with replacement of the frame.