Cara - I've got the same issue too.
Brand new SD card, fails to format, gets to about 20% and then the format screen disappears.
I took the card to my laptop, inserted there, formatted it, and copied a file to it, without issue.
put the card back into the phone and it says "corrupted" and attempts to format yet again with the 20% and disappears.
I then took an 8G card, inserted into the phone, comes up as "corrupted" tried the same steps, same issue, rebooted phone with an with out the cards in .. no matter what each time the card inserted into the phone fails to show a format screen above 20% and at next insertion or power off / on the message appears the card is corrupt.
The phone is less than a week old. Of course the family member that this phone was given too didn't keep the packaging, the receipt was tossed also so we may end up having to get Boost to replace the phone.
Hello TG2, what you are describing is a device issue. We recommend you contact LG at 1-800-793-8896 since the phone is under a one year warranty. You can also check and make sure the SD card is compatible with the phone.