Using megaupload

Hi,
I have Windows Vista Home Premium on my HP laptop. I am trying to download
files using megaupload.com. It was working fine last night, but today when I
try to download it doesn't work. The "save" or "open" window pops up, but
when I click save, it doesn't go to the screen that allows you to say where
to save it. I tried it from my desktop computer downstairs and it worked
fine. What could be wrong?

Adina