For some reason the server isn't allowing PHP to save that file.  The next thing I'd check is if the server disk is full (Check under: Admin > General > Disk Space or try to upload a file via FTP).  After that check if there's tens of thousands of files in the uploads folders.  Some Linux versions have a limit on how many files can be in one folder but it's usually 65,535 or more.  See if you can manually upload a file to the uploads folder via FTP.

If none of that helps, or you'd like us to take a look, can you put through a second level support ticket here:
https://www.interactivetools.com/support/email_support_form.php

Thanks!

It looks like a file permission issue.

Can you please check if the chmod/permissions for cms/uploads folder and sub folders are set to 755? They should be 755, 775, or 777.

Thanks,

Warning: imagejpeg(): Unable to open '/public_html/cms/uploads//thumb/march13_001.jpg' for writing: Permission denied in /public_html/admin/lib/image_functions.php on line 70 Error saving file!