No .nds file when unzipped

I'm using a mac but whenever i download roms and unzip them with stuffit expander i only get one file which is an .nfo extension. can anyone help please? Thanks

Use WinRAR to extract the files..
http://www.rarlab.com/download.htm

7zip is a good one too. Don't know if it works for Mac though. It's free and never has nag screens..

Use winrar if it still doesnt work use download manager to download your game and then extract it

No matter what program I try to extract with ( iv used about seven of them now) it always comes up with an error with the letters "CRC" in it. I can see the .nds file but when i try to extract it wont work.

Redownload the file again using download manager.
Use either Flashget, Orbit Downloader, and Free Download Manager.Search for it at here.
www.softpedia.com