Many computers here have a virus if you plug in your USB memory stick, and then later plug the USB memory stick in your own computer, you find that the folders on your USB memory stick are hidden and also the option to unhide the folders (change attribute) is greyed out so that you cannot unhide them (forced hidden). I found a website
http://www.raymond.cc/blog/archives/2009/05/01/reset-system-and-hidden-attributes-for-...used-by-virus/
that deals with this topic.
One method is to use the cmd command prompt. However, it has been proven that to use the command prompt, you must have an IQ over 93.26. Unfortunately, I couldn't figure out how to navigate to the USB memory stick using the command prompt.
Another method given is to use the software iReset (See screenshot). You just drag the offending folder to the cross sign and press reset. (2 mouse clicks total.) I can verify that this software works. Problem solved.