I just realized yesterday when trying connect to my hotel AP it worked first and then it just got disconnected. Retries to get back access gave always the Link local IP address...

But, it looks in my case that the N800 Bluetooth is giving this problem: It only occurs if Bluetooth is turned on on N800. I noticed this because when I browsed the web I had no problems... not even after long surfing period. But after I opened MaemoMapper, which turns on the Bluetooth automatically, the connection dropped right away. I was not able to get connected or stay connected with MaemoMapper running. Once I closed it and Bluetooth, the WiFi started working again without any issues!

So, could it be that the Bluetooth and the selected channel on the AP is at the same (or too close?) frequency band? They both are at 2.4GHz... but I assume they should not be exactly at the same frequency band?