Hmm so the file upgrade.php is present at /home3/lloyd32552/public_html/forum/install/upgrade.php?
Seems really weird that it's still throwing the error, the only other thing I can think of is a file permission problem, but it should generate a different error in that case.
What if you open up the install.php file and add
PHP Code:
chdir('/home3/lloyd32552/public_html/forum/install');
right before
PHP Code:
require_once('./upgrade.php');