Boot from a 32GB SD card fails except in safe mode

Hey all,

I have a class 10 16GB SD card that I use to sometimes boot my MBP (2011) into snow leopard so that I can still use rosetta. However I was getting short on space on the card so bought a class 10 (48MB/s) 32GB SD card and again installed snow leopard. With the larger (and faster) card I can still boot - but only using a safe mode (shift-down) boot. Booting normally just reveals a blue screen after the gray OSX screen has gone.

It's not a huge issue, but it would be nice to be able to boot normally from the 32GB SD card as I do need the space. Any ideas on what may be causing the problem? I'm suspecting the graphics Kext....

Thanks.