For years I have named files using a hyphen, ie 12-3456-1 REV 0.dwg, but today I am not able to open or save files containing the hyphen. Get an error message of "invalid character in file name". I've renamed such a file with the hyphen removed and it could be opened, but not "saved as" with the desired file name using a hyphen. Also could not save using an underscore in place of the hyphen. I have not knowingly changed any system variables. These are files at work which are referenced and requested by both my company and its customers by existing file name, so renaming hundreds of files is not an option. Any suggestions on a fix for this? Any ideas would be greatly appreciated!