File extensions in XP
 

I have Windows XP and when I try and rename a file, it won't accept it unless I put in the file extension. For example, if I want to change the name of a file from 'picture' to 'pic', I have to put .jpg as well or the file is unreadable. It's the same with all files, it never used to be like this.
Does anybody know how this could have happened and how I can change it back?

There's a feature in Windows which I never understood why it was ON by default. It appears that you're the use-case for such a setting. :)

In Explorer ("My Computer"), select Tools > Folder Options, select the View tab and check the box for "Hide extensions for known file types."

This is the first thing I turn off on my machines, as I like to know what the extension for a given file is. Alas, if you're intent on renaming a file without providing the full extension, this is your solution.

And apparently the choice most users desire, as dictated by Microsoft's defaulting.

If you select hide extension from the folder options, XP will maintain the same extension when renaming a file.

To check it go to windows explorer->tools->folder options->view. Look for "Hide extension for known file types".

HAH, SUCKER! I beat you by two minutes.

This is true even for the Administrator user on Microsoft Server OS's, which surprises me because ITs pros want to see all file extensions, as well as all system and hidden files.

Thanks a lot, I've been sorting out all my mp3's and it was a pain in the arse writing .mp3 every bloody time!