I have had problems with my airport express network since downloading a security update. I am running Tiger 4.2 on a 15" G4 powerbook, Panther 10.3.9 on a 17" powerbook and an old G3 iMac. The network had been running beautifully for 12 months then problems began with the 17" powerbook running after downloading an automatic security update.
The problem then spread to the other two machines over the next two days-also after the security update -I initially thought that it was just a wireless dropout and have undertaken the usual measures of unplugging the base station as well as the DSL modem(Dlink) then trying to reconnect with just the ethernet (I was getting a self assigned IP address at this stage) but eventually was able to connect the machine in this way.
I also used the Airport express setup and the airport admin utility trying various changes each time.
Eventually I was able to get 1 machine connected via airport (without being able to select the "share IP addresses") (if I try to use the same settings on the other mac I lose the connection altogether)-so running a network seems out of the question.
I now have the additional problem of the connection being lost totally if the mac goes to sleep! I have read so many threads on forums (including one that mentions reverting back to a previous security update)
Any ideas or suggestions would be appreciated.