I organise my media files by renaming them in capital letters. Recently, a dialogue box appeared telling me the file could become unusable if I continue, so I chose not to rename the file. Why is this happening? The computer is running Windows XP.

By way of background, the Windows file system is case insensitive, meaning that a file named in uppercase, lowercase or a combination of cases is exactly the same and can be accessed using any case variant on the file name. However, Windows uses a case preserving file system, meaning that the case used to name files and folders is preserved, but is not significant (as the file system is case insensitive). Therefore, renaming a file into all capitals should not be a problem. From your description of the issue you may be accidentally removing the file extension of the file when it is being renamed, triggering the warning. The file extension tells Windows the type of each file. For example, Word documents have the extension .doc or .docx telling Windows that the file is a Word document which can be opened using Word. If you remove that file extension then Windows does not know what type of file it is and it may become unusable as Windows will not be able to open the file when double-clicked, as it has no idea what program should be used to view the file. Therefore, you need to be careful when renaming the files so that you don’t remove the file extension. Alternatively, you can disable the display of common file extensions in Windows so that you don’t need to worry about accidentally removing the extension. To do this, in Windows Explorer or My Computer, go to the “Tools” menu > “Folder Options”. In the window that appears, click the “View” tab and tick “Hide file extensions for known file types” and then click OK to save and close.

If you find that all your files already do not have a file extension displayed, then the setting to hide file extensions is already enabled. In this case if you are still receiving the message about the file being unusable then something else seems to be in play, so please contact me again for further advice.