how fast is your internet connection? What is the file sizes you are trying to download?
I am assuming that you have a relatively good connection but are trying to download a large file. When it hits 99%, it will stall for a second, you will see a copy file window pop up, then after that finishes, it will hit 100% and you can open it. If you have a really slow HDD (5400rpm) it could take a little while.
it isn't because of his browser, the files just take a second to copy over from the temporary internet file location that it initally downloads to, to the location he specified. Some systems do this slower than others.