I've never had a problem renaming a file or files in a group, now a message
pops up & says that the file may be unusable if I change the extension.
I'm not doing anything different.....is a setting changed ?
I never changed an extension...just right click & type in the new title.
The extension is the last three (usually) characters in a filename,
after the dot. For example, in the filename iexplore.exe (the
executable file for Internet explorer), the extension is .exe.
By default, the extensions are hidden when you display them in My
Computer, so you may not realize that the file whose name you were
changing even had an extension. It's a very poor default, in my view,
and, assuming that you are set that way, I recommend that you follow
Richard's advice and change the setting so that extensions are
visible.
The extension tells Windows what to do if you double-click the file.
So if you double-click an .exe file, it will execute it. Or if you
double-click a .doc file, it will open it in Word. But if you change
the extension, Windows will either not know what to do with the file
or open it in the wrong program. For example, if you change
anyfile.doc to anyfile.exe, Windows will try to execute it when you
double-click it (which won't work); change it anyfile.zzz, and Windows
won't know what to do with it at all.
