USB on macbook pro 2011

Hi,

I have a macbook pro 2011. I have transferred some pictures into my WD passport (macbook version) and brought it into a photography shop for digital printing today but the staff was unable to open the files (none of my files are viewable, since the operating system of the computers is windows, I assume)

However, when I got back, I quickly plugged in my external hard disk to check if any files are missing. After that, I tried to transfer the pictures into a USB pen drive, so that the pictures can be viewed at the shop for digital printing. The problem now starts, as the USB drive can only be READ only, which is strange, because I was still able to edit my files on the same USB drive before. (yesterday, same day etc)

I tried to erase that USB pen drive on disk utility but all options are greyed out.
What's wrong??

THanks

can you post a screenshot from disk utiliy?

I'd suggest you need to re-partition and format the pendrive by select the pendrive at 'disk' level not partition level

http://img196.imageshack.us/img196/4263/screenshot20120806at110.png
http://img38.imageshack.us/img38/4263/screenshot20120806at110.png
http://img838.imageshack.us/img838/4263/screenshot20120806at110.png
http://img52.imageshack.us/img52/4263/screenshot20120806at110.png
http://img819.imageshack.us/img819/4263/screenshot20120806at110.png

With the drive selected (in your screenshot) go to the erase tab and select msdos fat as the format

no I couldn't. All options are greyed out (refers to the screenshots), sorry that the images could not be viewd but I believe they can be now

What sort of flash drive do you have?

Does it have a write protect tab/switch?

unfortunately no is there nothing that I can do about it?
I'm just really surprised how the USB pendrive becomes READ ONLY out of a sudden

Do you have another machine you can try it in?

ya I tried it on my brother's desktop (windows) but I also failed to reformat it because it is READ ONLY according to the warning message

Then there's either a write protect switch or the device is failing

okay, thanks