You are running an app on your Win 7 machine that is conflicting with the Cruzer. It could be Samsung’s Kies or one of a number of others. See if this thread helps you: http://forums.sandisk.com/t5/All-SanDisk-USB-Flash-Drives/Windows-7-Explorer-not-showing-drive-while-it-shows-in-computer/m-p/290694 It refers to several apps known to cause problems.