I have managed to share my internet connection from my aspireone netbook (Ubuntu 9.10) to my PC running XP. This seems to work fine - after I unplug the lan connection and then reconnect. However, if I try to do the same with another Ubuntu PC(9.10), it just says "no connection". I have checked all the settings on network manager like sharing etc and nothing seems to work. I have also tried a cross-over cable. Still no luck. I even downloaded firestarter - still no joy. What can be the problem?

My netbook is connected via wifi to my router. I know that the simplest solution is to buy a usb wifi for my PC, but this seems to be a waste and it doesn't suite me to do this.