Hello everybody!

I always had an ad hoc wifi network between my ubuntu 12.04 machine (as host) and my win XP (as guest) in order to share the web access.

I've not been using it for some month and now it's not working anymore (that's really weird!).

If I look for wifi with XP I cannot see it, but if I add it manually I can see it with max signal of course.
Then I click on connect and, I'm asked of the pass and then after retreiving IP adress and so on it get "locked" to this net but it says "not connected" and the button turn into disconnect.

What could be?
This are setting on ubuntu:
Mode: ad hoc
Band: automatic
All user: yes
Method: shared with other PC
Ask for IPv4 to connect: no (I'm not sure about this, I don't want to give XP a new IP)
Password WEP

On XP should I do something special?

Thank you a lot!