MT4.21com - the archive index has a whole bunch of [/mt:Ignore] tags misplaced, so entire archive listings are ignored.. the first few types of archives on that template are ok, eg:
[mt:Ignore] [!-- List of category archives, if category archives are enabled --] [/mt:Ignore]
but then with most of the remaining ones the [/mt:Ignore] tag is placed right at the end of the code for each archive listing type, rather than at the end of the 'help' message as above.
Also I entered ticket 81593 on fogbugz for another issue. A new install fixed the problem, so if someone can please delete that ticket it would be appreciated.
Reported on Movable Type 4.2
This happens sometimes. Sometimes it doesn't insert the data correctly during an upgrade.