I Recently (a couple weeks ago) downloaded the complete series of Seinfeld, all in varying file type. I Watched them in sequence according to season and to airing date, and all was well. All of the files played fine with my media player of choice ("BS Player"), and once I had finished, I went onto watch some other TV I had previously downloaded (The U.S. Series of "The Office"), and after then, some other film and then some music, over the following weeks (keep in mind all of these files are all on the same Hard Drive). Later then, More recently, I Went back to watching Seinfeld. The episodes played well as they did before- with the exclusion of a few in Season 7.

I Have not tested all of the episodes in the season, but upon inspection, the majority of them are experiencing this problem; the problem being simply that they don't open! BS Player says that the files are either damaged or that the codecs to play the files are not on my computer-- however I am certain that the files DO have the codecs, and I am pretty sure that they are NOT DAMAGED either.

I Have played the files with other players (such as VLC, Media Player Classic, and Windows Media Player), too, only to the same result; of them not opening.

Seemingly the only way that I can differentiate between a damaged file and a non-damaged file are the way that the icon shows in Windows Explorer. For example, the below image is how explorer shows the information of a file that is non-damaged... ...and below is how a damaged file appears...

The most disturbing and confusing part of this, though, is the last episode in the season- It opens, but not as a video- Instead, as a 1 Hour, 16 Minute, and 35 Second Audio file! The file plays a song for the first 4 or so minutes, and then is pretty much silent (except for some extremely quiet noise) until the last minute or so, when a random array of chopped up sounds and beeping noises play. I Do not recognise the song at the beginning of the file, but by the sounds of it, it is a song by the artist "Mr. Oizo," who's complete works I downloaded a couple weeks before now; and a bit before then I had finished downloading season 9 (not affected by these problems) of Seinfeld.

I'd also like to note that the file I told of earlier (which played audio instead of video) reads as the same size as the other files in the season (around 175 MB) and also opens as a video clip.

I Have NEVER experienced any of these problems in the past, and they seem to be only effecting the one season of my downloaded TV. The problems have not arisen with any of the other files on my Hard Drive, or any of the files downloaded around the time or after the time of which I downloaded season 7 of Seinfeld- or at least to my noticing.

I Use the hard drive these files are located on almost every day, so could that be the cause of these problems? Is this a sign that my HDD is soon going to die?

If it helps, the HDD is a Western Digital MyBook 1.5 TB 7500 RPM. It is connected to the computer via U.S.B. 2.0.

EDIT! I noticed that this problem is now occurring with Season 9 of Seinfeld- and, presumably, other files on the drive I have yet to check.

Please, If you have ANY IDEA AT ALL on what may be causing this or how to fix it, do tell me!