I have this problem ever since I got the N800 (used) a couple of months ago and have flashed the unit four times but the problem still exist.

Description:

1. The unit does not allow me to save anything on the external SD cards (both internal and external slots). Whenever I download and save a file onto the SD card, the file appears in the file manager but when I remove and replace the card, the file disappears. In the same way, any attempts to format the SD card using the unit will appears to work, only to have the original files reappear again after the card has been re-slotted back.

2. I cannot transfer files from the card to the unit's memory (and vice versa). The message "Connection error" always appear.

3. I can read and access files on the SD cards that have been saved using an external card reader but after the N800 accessed or used the files, it always render the card "unformatable". Every time I try to format the card (using an external reader), the error message "Write protected" appears.

Is there a hardware problem?

First, make sure the card is NOT write-protected -- that little tab affects external card readers but is inoperative in the N800.

I'm assuming you've tried this with only one SD card so far and have only one? If nothing else works, back up your SD data to a PC using the USB connector and then see if it helps to use the low-level Panasonic formatter -- it's in the first or second post in my first dual-booting link below.