PhotoPost Community - Couple of Problems

First one is some of my users are getting the following error message occasionally.

Unable to create image
[/home/scribbl/public_html/photpost/uploads/681/Paradise_Found.jpg].
Please contact system administrator.

I asked the user to email the pictures she was trying to upload. She did, I tried to upload and it worked fine. What could be the problem?
Several other users have gotten error messages about the files they are trying to upload are not proper jpgs. when in fact they are.
What is going on with PhotoPost?

Second problem is the member list is way screwy. When I click on a specific letter (like "M") to view all users whose names start with that letter, I get a list of 10 per page. When I click on page 2 to see more users whose names start with "M", it jumps back to the first page of "A"

Can anyone help me with these problems, please?
URL to my site is

http://www.scribblesonline.com/photpost/index.php

TIA!!
Lisa