I had the same problem - my mini-SD card in an adaptor would not work in the memory card reader in my Inspiron 6400.  I found that it was because there are exposed contacts on the bottom of the adaptor where the mini-SD card contacts engage and these were shorting out on the other contacts inside the card reader for xD cards.  I put some Scotch magic tape over the contacts and now it works! I found the tape had to go all the way to the edge where the mini-SD goes in otherwise it can catch on the contacts inside the card reader when you remove the adaptor.  I used the magic tape as it is thin and there is not room for thicker tape. (see photo)

 

 

You know, I had the exact same thought.  I just hadn't taken the time to experiment with it.  My card reader has a problem now, so I can't play with it.  I sent it back and they said the mobo would get replaced.  It didn't and the problem still exists.  On top of that, they lost the wall half of my power cord too!  So, now I have my dual core e1705 computer with ~30min of battery and no way to charge it!!!!  Thanks Dell! :manwink:

 

Geoff