I recently purchased an 8 GB usb flash drive with the brand name SFINC. Can anyone explain why this device hides files once a certain amount of data is saved to it and you cannot retrieve it. You have to format the flash drive in order to gain back the space.

I think that has something to do with a maximum amount of files allowed with the FAT formatting used. 65,000 +-. Search here for more info on that topic.

I have the same problem, I purchased a new 8Gb drive last week and have found that there appears to be a problem with the file management of these sticks. It makes no difference if you use the stick under Windows or Linux nor if you format it to FAT VFAT or VFAT32, it is always the same result.
I don't agree with the number of files theory as I have copied a set of photo's over to the stick, approx 1000 files in 4 folders, sometimes all the folders are there with content, other times there is just an empty folder; some of the photo's in the folders display only a blank screen when viewed i.e. no content. When the files are deleted they appear to go but the stick no longer has it's full capacity available. I attempted to fill the stick as a trial and then delete all files, explorer showed the stick as empty but it still retained 2.5Gb of allocated data space, my nice new 8Gb stick was now only 5.5Gb. Checking on the SFINC web site they recommend re-formatting the stick, great way to manage your data and not a very reliable backup device. I haven't tried formatting it to ntfs or straight linux yet, I guess that might be another trial.

Derek

Just a quick follow-up on these sticks if anyone is interested. After trying a couple of sticks to no avail some research indicated that a lot of high capacity sticks coming out of China are fakes. So I popped the cover and had a look, sure enough these sticks are fitted with a Hynix 2G chip (part # HY27UF082G2A and an Alcor AU6980 controller chip. The controller chips are programmed so that the stick appears to be 8G when in fact it is not and has a much smaller memory capacity. Hence the problems when you try writing files to them.

Derek