Hi, I have a N810 since last week.
I installed all repositories from http://gronmayer.com/it/ and several apps, including rtcomm beta update, with no problems.
This night I felt brave and tried an apt-get upgrade as root and all went fine, but DHCP seems to stop working. When I connect to my AP I get no IP, no nameserver, no routes... nothing.
If I issue "udhcpc -i wlan0" as root from terminal, all goes fine.
Any ideas?
Yes, I know, I should reflash, but I'd like to understand the problem and fix it.

Many thanks in advance.

The problem is you used apt-get to upgrade, there is no problem with apt-get as long as you realize that you can not use it to update the system, you can install and remove stuff all day long. But apt-get does not understand all of the maemo stuff so you probably updated the kernel level stuff with out updating the maemo world. You should alway use the apt manager to upgrade stuff. Unless you can reverse the apt-get ( I don't know a way) you will have to reflash. Don't run apt-get upgrade until nokia says its safe.
That is just my $0.02

Strange!
A second reboot after the upgrade fixed this issue... it seems a windowesque behaviour to me, but now it's fine