When the site came back up, it looks like half the SEF component was not working. URL's within the page were being rewritten to be SEF (Search Engine Friendly) but the server did not know what to them with them when requested.
For example, to actual vbulletin URL of this thread is
http://www.pokerforums.org/general-online-poker-discussion/28391-dont-let-bad-urls-stop-you.html#post229910
However the SEF URL is
Dont let bad URLs stop you
vbulletin was rewriting the URL to present the SEF one, however the server did not know how to respond when that URL was requested .
TBH - The admin would have probably preferred if I wasn’t screwing around while they were fixing things, but it's not like I was doing anything malicious.