I am a computer consultant, dabbling in cameras and photography. There are two significant problems on flash memory devices. One is the type of USB port you plug into, and secondly, ARE YOU TERMINATING the USB device before removing a card. My experience has shown me that there is a critical problem with the power that the USB port introduces to flash memory devices in order to power the memory.
Without going into more detail than this posting situation allows, the first problem is the use of flash memory devices, ie thumb drive, camera memory cards AND PERHAPS even your digital camera when plugged into powered hubs that use an AC wall adaptor to power the hub. I suggest that you never plug a flash memory device into this type of hub. Only use ports on the computer. If you must use a hub to expand the capacity of your computers ports, use a passive hub.... no AC adaptor plugged into the wall.
I've personally destroyed two thumb drives and one memory card before isolating the source of the problem.
Now, there is one other problem. Usually when you plug a flash memory device into your computer (XP or Vista), the operating system discovers the device and powers the port into which the device is plugged. Often, there will be a USB telltale in the System Tray (Lower right hand corner of your screen). The telltale looks like a little grey card with a green arrow above it. That's the system tray item indicating that you are using an external USB device. If you hover the cursor over that card/green arrow, you should see a message that says safely remove hardware. This message is important. The USB port must be turned off before you pull the memory device out. Otherwise, if you do not turn off the port, you may create a slight spark when pulling the device and permanently damage the memory card (AND I wonder,,, you camera if linked directly to the computer?).
To disable the port you double left click on the grey card/green arrow. It opens a dialogue box, in which you pick or select the drive you want to remove and then click "stop". You will then be advised that it is safe to remove the card.
In some cases, where intervening devices are use, such as printers with media ports, you may not get this telltale and control symbol.
I contend that your memory card MAY be damaged beyond repair. Can you re-format it? Even if you can, I do not think I would trust the card.
I've encountered this problem personally and on client computers. I also saw it on a 160Gb external hard drive that could no longer be used. In this case the client was using the external hard drive for his "scratch" disk in Photoshop and doing editing over the USB 2.0 cable. USB 2.0 is not nearly fast enough to be the working drive for image editing. The drive was destroyed. Fortunately, it was replacable under warranty since it was a Western Digital and less than 6 months old.
You have to be careful on USB. Never remove a device without shutting off the port first.
