I currently am on an early 08 Macbook Pro 17". 2.4ghz with 4gb of RAM. I've recently purchased a 32gb SDHC card. Trying to create a bootable emergency drive with os installed on it. I plugged it into my Mac via usb adapter and it mounted fine. Was formatted as Fat-32. So went to disk utility and reformatted as 1 partition, GUID, Mac Os Extended (journaled), to make it a bootable disk for the os. When doing this it appeared to complete fine, but disappeared from my desktop. No longer showing up in finder. Still mounts in disk utility though. Tried different ports, rebooting, and reformatting,, with no resolve. Reformatted it back to Master Boot Record/ Ms Dos, and it mounts again fine in Finder. Can drag data to it with no issue. Reformatted again as GUID and again it disappeared from Finder and desktop. This is where I'm confused... In Disk Util it completes the formatting and shows Map Scheme as GUID and journaled. The odd thing is that on the left where disks are mounted it shows the indented partition as disk3s2. Even though I've renamed it when formatting. It will maintain the name formatting back to Fat32, but not with GUID. Also if I try to repair disk it fails. " Disk Utility stopped repairing disk3s2 because the following error was encountered: Filesystem verify or repair failed." Does not fail doing repair as Fat32. Figured I would just try to install Os anyways and booted to install disk. When booted to Os it did list the SD card as an optional drive, but had the exclamation point listed as not being in correct format. Instructs to reformat as GUID. Went to disk util and reformatted and it disapears from select a destination. My questions are.. am I missing something technical about these cards and formating as GUID? Why will this mount in Finder and also in the destination screen for install if its formatted as FAT32, but wont show up in either as GUID? Why does it show disk3s2 similar to windows partitions, even though it was formatted as GUID and renamed? Not sure if I'm having an actual hardware issue with card, or have to do something to modify this to be useable. Tried this on a newer iMac with same result. Thanks for any input and sorry for the novel.