Sorry I wasn't more clear.
The bottom line is that if I try to save a photo onto the SD card, it hangs at the downloading stage. The green bar advances all the way across during this stage, then the green bar goes away and it continues to say downloading... but it never advances to the next stage. I can't even cancel the sequence, it just hangs forever and I have to restart SGP.
As soon as I change to the internal drive, everything works perfectly.