Hi Dave,
I found a conflict between this hack and your other hack:
'Mark One or All Read (markallread.6.1.php) '
Id you switch the language and click markallread right thereafter, markallread has a problem with the referrer (the url still has that extra "language=english") and then IE5/MAc gives a blank page instead of a refresh.
I think the problem could be in this hack and not in Markallread.
greetings
carl