One our regular patrons comes in with a ziplock bag full of flash drives, and then will spend hours copying text and images from websites into Word documents. He then saves these Word documents to the flash drives, and he also saves every email attachment he gets on the flash drives.
I trust this particular patron to know how to use a flash drive, so I was surprised one day when he comes up and said,
Your computer is giving me a flash drive error - it is saying it is full or write-protected, but it's not.
I went over to his computer, and sure enough, when I tried to save his file, I got the same error. I checked to make sure the drive wasn't physically locked, and also that it wasn't full - according to the properties, he had less than 30mb on a 1gb drive.
I was afraid the drive was corrupted somehow, so I took his drive back to the reference desk with me, telling him I'd look into it. A simple Google search for "can't save to flash drive" led to a thread on cnet forums.
The thread suggested this error can happen when you reach the upper limit on the number of files the root directory can hold. I had never heard of this before, so I took a look at his flash drive's root directory - sure enough, there were something like 700+ files in it.
I took the flash drive back to the patron and explained what I learned. The solution, I told him, is to temporarily cut/paste one file off of the drive to the computer, which will let us create a folder on the flash drive. Then, he can move files into the folder, and create additional folders, and start organizing files that way, instead of leaving everything in the root directory.
He did this, and it worked perfectly.
I had no idea disk directories had such limits, and I remarked to the patron that thanks to him, I learned something. This particular patron is always friendly and grateful for any help we give him. In this case though, he was extra cheerful - he spent the rest of the day letting everyone know that he taught me something.