It could be that you're suffering from the trailing carriage return syndrom.

If you created the file on a windows machine and uploaded to the empeg without passing it through an editor capable of saving it in Unix format (linefeed only as line termination, while Windows uses carriage return + linefeed)
That causes the empeg to try to pass on the script not to /bin/sh, but to the non-existing /bin/sh^M (^M=ASCII char 13=carriage return)

If that's not the case then I'd be suspicious of the
cd /drive0/var/bootsound
./pcmplay

Is your pcmplay file in /drive0/var/bootsound?


/Michael