Wilson Tsoi , Mar 23, 2006; 07:37 p.m.
I've never experience this with the A620, yet. Is it possible that you worked images in the SD card in PhotoShop and stick the card back in camera? Even then, that doesn't explain the camera shutting down.
Before you do anything, if you have images you need retrieving from that SD card, stick the SD card to your computer and run Sandisk "RescuePRO." It will automatically pull out any corrupted files.
After that, I'd say do some test shooting and isolate problem to either the camera or the card. Whatever ending up being at fault, exchage it.
Good luck. ^_^