I have three SanDisk flash drives (aka, thumb drives, memory sticks...) and I'm trying to back some data up onto them. However, they keep showing up as COMPLETELY BLANK. Sometimes when I 'safely remove' and reinsert, they work for a little while, then show up blank. Sometimes when I insert them, they show up blank from the start. These were all bought at different times. What on earth is going on? An example of one of the oddities is if I go into one folder, I will see the little previews for other items in subfolders. But then, I will see a series of blank folders, click them, it will tell me it is empty, I will go back to the folder I just came from, and IT will read as empty as well. Then when I go back to the folder before that--it shows up as empty, too! Even though it hadn't been just moments before.

This is extremely problematic since my nephews spilled cola all over the computer earlier to-day and I want to back up my info (this problem has existed before the spill). Please help!