automatically-generated mystery files

In Windows Explorer, I notice that some of my folders contain files that are only 1KB and appear to be some sort of invalid copies of the real files, sharing the same name, but preced with a ._ (for example, IMG_0166.jpg has a buddy named ._IMG_0166.jpg). These files are also dimmed out a bit when viewed in Explorer. I'd like to know how these are generated, what their purpose is (if any), and if there is a way to keep these from being generated.
Thanks!

 

The images are in a folder that I uploaded a few months ago on my company's server. Those files are fine, it's the files whose names start off with "._ ". I think this has happened with other file types besides jpgs, not sure. The files always share the same name as the original "real" file with the exception of the ._ prefix. These files, despite having real extensions like ".jpg ", cannot be opened. I don't know how these files are generated. I think it only happens once the files have been opened. I'm not sure; I've never paid much attention. I could send you a screen shot of the explorer window if that helps.

 

michellewesten--I understand you cannot open these files.
I suspect malware.
You may want to try the procedure here
http://www.windowsbbs.com/showthread.php?t=37074

 

Is it possible that they are thumbnails of the original pictures that are generated by some program you use to view them?

 

yes, they seem like they could be some sort of temp file. I don't understand why they stay in there. I will try running a bunch of scans to see if there is any malware on my computer.

 

michellewesten--Paraphrasing what Steve R Jones has said, in what folder are these files 'whose names start off with "._" '?
If you right click on one of them and then Properties, does the info on the various tabs give you any information about their source?

 

When I go into Properties, the only thing it really says is that it's a hidden file. It says it is, indeed, a jpg file (though the computer otherwise does not recognize it as such). I'm not sure what you mean when you ask what folder it is in. It's nowhere on my hard drive; it's on my company's server and is called Santa Maria Discovery Center. Also, I noticed all these "mystery" files have the same date: 2/10/06 and all have almost the same time, spanning only a couple minutes. These dates and times do not match up with their "real" jpg file counterparts. I appreciate all your help!