Try cleaning all temp files, that sometimes workes with things like this:
Please download
ATF-Cleaner
And then run ATF-Cleaner:
First check
"Select All" , and then remove the tick infront of "History".
After that click Empty Selected.
When you get the "Done Cleaning" message, click OK.
If you use Firefox or Opera as browser:
Click Firefox/Opera at the top, and Select
Cookies and
Cache from the list.
Click the Empty Selected button.
BTW, are you using a download manager of some sort?