Weird Problem with videos not opening depending on cable.

I have this weird problem occurring. I have an external hard drive that can connect via eSata or USB. For some reason if I use the USB cord, some of the videos on the hard drive won't open. Media player classic gives a "Cannot Render File" error, and other video players give similar errors. However if I use the eSata cord, it works perfectly. What could be causing this? Thanks in advance.