Oh my gosh, I feel like an idiot.
*smacks self*
I just had the thought to check the pam limits on this user, and he was only allowed to open 5 files at a time... which is less than this script needed.
So, I updated the value to 30, and... bam! It worked.
Again, thanks for your more than helpful responses, even though I was the one who didn't tell you the important info
.
-Michael.