Error messages when accessing password page directly

If a user attemps to access a protected node such as node/3620 they are redirected to protected-node?destination=node/3620 and eveything works fine.

However, if they reload protected-node?destination=node/3620 or try to access protected-node?destination=node/3620 directly (e.g. by copying and pasting the URL into another browser) they sometimes get...

warning: Invalid argument supplied for foreach() in /usr/local/pem/vhosts/******/webspace/httpdocs/modules/node/node.module on line 561.
warning: implode(): Invalid arguments passed in /usr/local/pem/vhosts/******/webspace/httpdocs/modules/node/node.module on line 565.
user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 query: SELECT n.nid, n.vid, n.type, n.status, n.created, n.changed, n.comment, n.promote, n.sticky, r.timestamp AS revision_timestamp, r.title, r.body, r.teaser, r.log, r.format, u.uid, u.name, u.picture, u.data FROM node n INNER JOIN users u ON u.uid = n.uid INNER JOIN node_revisions r ON r.vid = n.vid WHERE in /usr/local/pem/vhosts/******/webspace/httpdocs/includes/database.mysqli.inc on line 156.