This can be set if you place at the top of your index.php file, after the <?php tag:
Code:
ini_set('upload_tmp_dir', '/home/USERNAME/public_html/tmp');
or
Code:
ini_set('upload_tmp_dir', '/tmp');
Choice #1 means that only you can access your temp files #2 means anyone with an X10Hosting free account on your server can access them.
I'll mention to the staff members this is happening, but I can't give you an ETA on it being assessed, so you might want to try one of the above to fix it temporarily and then try deleting it and see if it works periodically. When it does, it will be method #2, so there is some benefit still to using #1.
Do you have another account? Your forum account is not linked to any hosting account. If you can provide your CPanel user name, that would be great. This will need to be corrected or eventually you will be suspended for inactivity even though you sign on to the forums.