Samkeymaster

I have alot of images I need resized and normally when I add the images I set the custom size and press convert but when I do I get a red X saying faild to convert on them, seems it keeps saying the images are in use or opened by another program. I know enough about computers and how to use them to know they are not in use by any other program. Now this only happens if I use the same directory to save them as they are open but I dont want to have to create another directory everytime I need to convert pictures. Any suggestions?