Why am I recently unable to download video files in IE8?

Lately I have noticed that the video files that i download stop in the middle at any random % completion. These files are mostly about 600-700 MB. I am using Windows 7. I am a regular downloader of files & this had never happened before. This does not happen on other browsers like firefox (thankfully) 🙂
Plus there is no network issue at those times as well. Any ideas???