Okay, I was going to tell you to format it at first, but then you said you did, and that didn't help, so...
Like Berserker has stated, try deleting game saves on the memory card. Game saves that you can live without. Then, if there's still a problem with the memory card...
Get a new one. You can purchase a 16 Mega Memory card at your local electronics store for just 26 dollars or less, and you can have double the space, for a reasonable price. You can also now get a 64 MB card, which is only 36 dollars.
https://www.bestbuy.com/site/olspage....ry&id=cat08189
But, you should check and see, all ways possible, if you can fix the memory card. Like Berserker and me have stated, try deleting as much game saves as you possibly can, and also live without. That's all I can tell you, bud. Since, you can't really take apart a memory card and fix it.
It's just sometimes, some memory cards are defected. Sometimes, there's just too many game saves on them. Hopefully, you can figure out your problem.