May I ask do you use a mac. I have a horrible suspicion you use a mac b/c this would be unheard of on windows. Whilst the data itself might be fine, the small tabs on the file that the system reads is incorrect giving it incorrect info. So what you need is a file utility to repair it. Not such a big issue if you have those utilities.

As you probably know on a mac, flags that should be opened or closed are sometimes incorrectly set. On OS 9 & earlier you might rebuild the desktop to repair & perhaps run First Aide Utility.