I've registered! thanks for helping out!
as for the details of my problem:
1. Level 3 for ALL technologies (everything fully researched and plenty of tech points to spare)
2. 30000+ food surplus
3. all 25 villagers put on construction mode for one day
4. still no sign of the scaffolding for the 3rd hut
5. tried exiting and re-entering the game

umm... plz don't let it be a naughty buggy problem...