There are a couple of errors reported in your log. The most likely culprit is:
Message: WARNING: fsockopen() [function.fsockopen]: unable to connect to pkp.sfu.ca:80
indicating that your server is unable to connect to PKP in order to check for available updates.
Is your server firewalled or proxied for outgoing web requests?
Try turning off show_upgrade_warning in config.inc.php to see if that resolves the error.