Laptop sees Sandisk 4 GB (Class 6) SDHC, but not Sandisk 16 GB (Class 10) SDHC

I searched the forums and did not find anyone with this same issue.  Apologies if I missed it.  I have a Dell Alienware M17x R3 laptop that has faithfully read my Sandisk 4 GB Class 6 SDHC cards since I bought it.  I recently bought 2 Sandisk 16 GB Class 10 SDHC cards, but my Dell Alienware laptop does not see them at all.  I may as well be plugging in the plastic shipping blank they put in the card reader slot.  I have verified the new 16 GB cards work in 3 different cameras and even got them to work with the Dell Alienware laptop using an external USB card reader.  I called Dell Alienware tech support and they had no clue.  They just said it should work.

I have formatted the 16 GB cards via the camera as well as with Windows Explorer on the Dell Alienware laptop.  Although each formatting session was successful the card reader on the laptop still does not even see the cards.  I put the 4 GB SDHC cards back in the card reader and it sees them just fine.

I checked the card reader in my laptop to see if it has the latest drivers and it does.  I used the laptop’s Device Manager.  I had to put in one of my 4 GB SDHC cards in order for the drive to show up in the Device Manager.  I am using Windows 7, 64 bit.

Any suggestions as to what might be my problem?

I know this forum is a little old, but I ran into this issue today.

The Alienware  M17x R3’s card reader is NOT compatible with Class 10 SD Cards.

I upgraded my 32gb Class 6 to a Class10 and its a no go.  

Speaking to Dell/Alienware, they do not have a driver/firmware update to correct this so it must be a hardware limitation.