Can’t copy files to the server

I have a Windows 2003 for Small Business server. I have shared out a folder on that server so that people can save files to this specific folder. I put everyone as a user for the folder that is shared out. When I try and save a file to the folder I get “Make sure the disk is not full or write protected and that the file is not in use”. Both of those suggestions are not the issue. It has to do with some security setting that I’m overlooking. Any help with be greatly appreciated.