Sorry for doubleposting, don't want to mess things up
stinger2,
the hack does well in printthread.php on your forums,
did you edit anything hardcoded in showthread.php?
I can't imagine any templatecode messing the php code up

Please make sure, that you have the original vB showthread.php uploaded (in ascii mode) also, php v4 is required
if both give that codechange a try:
hook:
fetch hide tag
PHP Code:
global $vbulletin, $vboptions, $bbuserinfo, $db, $threadid, $hide_call, $postid;
replace by
PHP Code:
global $vbulletin, $vboptions, $bbuserinfo, $db, $threadid, $hide_call, $postid, $thank;
the $thank array should be useable without the globaliser ($thank comes from the post_thanks hack in postbit_display_start),
but maybe something's interferrring ....
'sid (clueless)