If you use Microsoft Word or Excel (or PowerPoint too, I guess), and have recently upgraded to Office 2011, be aware that these apps have an issue with file names that contain a forward slash (“/”).
It used to be that the only character that was “illegal” in a Mac file name was the colon, and that’s because the Mac would use that internally to designate folder paths. So if you had a “Widget” folder on your hard drive that contained the file “gidget.txt”, that path was represented internally as “My Drive:Widget:gidget.txt”.
When Apple moved the MacOS to a Unix base, they had to deal with a conflict. In Unix, the character that designates a folder is the forward slash, so the same file is represented by “/Widget/gidget.txt”. Apple dealt with this conflict by creating a layer above its Unix underpinnings that converts the colon to a slash and vice-versa. Applications could go on using the old-style designation, including slashes, without having to worry about what was going on beneath the hood.
But Microsoft is clearly doing things in a different way. Although it shouldn’t make a difference, the Microsoft apps are having trouble with the “/” in file names, and either refusing to open these files, or opening them as “read only”.
The bottom line is, don’t put slashes into your file names, whether they are meant for the Microsoft apps or not. If you have a file called “Info on 3/5/12.doc”, change it to “Info on 3-5-12.doc” or something similar.