Lately I've been feeling paranoid about going on FB. Many months back a friend said her credit account was hacked into using FB, and since then I've been very wary of going on the FB site. I still go on there every day

but only on my "internet computer." If I want to check my credit card account online, I close the FB window--dunno if that's gonna do any good.
Today I went to open some MS Word files from a USB device using my laptop. I was shocked that all the Word files had weird "square" symbols in place of the file names. I played it safe and didn't open any of my file on my laptop. I then plugged the USB to my internet computer and the files still have those weird squares. All the files are there but instead of showing the Word doc icon there is just a black paper icon with an unusually high KB numbers, and they can't be opened. I've no idea how that happened. It's a 512MB Imation USB that I have used strictly for six Word documents. The last time I used it was on the Internet computer. I did a scan using AVG and there is no virus detected. Can a USB just out of the blue corrupt your files?
I'm wondering if I got a virus on there, but then wouldn't it affect my computer as well?