MacBook Pro i7 2.0 won't recognise SanDisk Extreme Pro SDHC card

I have a 1 and a half month old MacBook Pro i7 2.0 running 10.6.7 on all the latest updates, and I recently bought a new Nikon D700 with a SanDisk Extreme Pro 45mb/s SDHC card.

The first time I tried to use this, it was read completely fine by the built in card reader.

I took some photos and tried to upload them which worked, and did this again the next day.

The Mac wouldn't recognise the card at all.

I thought the card was broken so I tried it in my Windows 7 machine, loaded completely fine.

I called up Apple support who got me to perform a memory reset and some other reset to try and fix the problem, which didnt help. They then suggested that I try another SD card. I did so, and it worked completely fine. Put the other card back in my Mac, nothing. I've even reformatted the whole thing and made sure it's on FAT32 with no joy.

Google seems to have no hint to the problem, so here I am.

Ideas? Anyone?