Millisecond Forums

Hello,
I'm using Inquisit to run an online study. I tried different computers to make sure it can run smoothly. Then I got one problem when I ran it on Mac: the stimulus isn't erased on the next trial. Here is the part of the script,

<block h1sh1_h1_d1d2d3>
/ trials = [1 = noreplace(human1_storyh1); 2-4= noreplace(human1_dilemma1,human1_dilemma2, human1_dilemma3)]
</block>

The following stimulus is always on the screen when trial 2-4 are running (it's in Dutch). 
"Omdat hij vindt dat hij toen te ijdel was en zich wilde bewijzen, zonder met zijn vriendin rekening te houden."
"Omdat het hem toen niet gelukt was om de top te bereiken, ondanks zijn ervaring."

I tried different ways to solve it, such as putting blank trial, or blank rectangle between trial 1 and 2, to cover it, but the stimulus is always in front, and can not be covered by blank trial. 
Notice that this problem only happens in Mac, and Windows computers and laptops are working fine. 
I put the material in the attachment. Please ignore the layout of the experiment, but you can see the problem. 
Is there any way to solve this problem?
Thanks in advance.