Windows vista question.... again?

I have asked a few questions on here about vista but here is my latest.......when I try to creat a folder by right clicking the mouse going to new and then selecting folder it pops up as "New Folder" when I try to rename the folder to what I want a dialoge box pops up and says "this file or folder does not exist" and makes me close it resulting in a folder caled new folder which I must then delete cause its useless to me how can I rename it? hope someone can help thanks .............also tried making a new folder with an existing folder name and that pesky message box popped up again so ya.......