Im very new to using Gps. Just got a Gt 31, and got a Sandisk 2GB SD card as reccomended. Put it in and formatted it a couple of times which was successful. After turning it off and on again it says "card unknown or unformatted" and after trying to format it, it then says " bad format"
Any ideas greatly appreciated
Do you have any other SD cards handy? If so try one of them in your GPS. I use a 32MB card in my GT-11 and have no problems with it. The files the GPS creates are quite small.
If not see whether your computer can read see the card and then try to format it FAT32. If that works see if your GPS can now read the card.
It may be that for whatever reason your GPS cannot read that particular card. That happened when I helped a mate set up his GT-31. The card he had worked perfectly fine in a digital camera but the GT-31 would not read it. So we agreed to swap cards and everything was fine till recently.
Just found a little 16MB card which is not on the reccomended list and it seems to work fine. Might have to say goodbye to the 2GB disk 
I been using 2 gig Sandisk for over a year or so with no problems.
You will find that a 16 Mb card will last quite a while.
Good Luck anyway
Just an idea but you didn't accidentally lock it, you know the little slide switch ?
Cheers Bob.
