Is less than WPA security on the wifi. It happens so often that I've gotten to giving just the short answer without writing the long why.
I have 3 machines in one room here. One Dell Win XP, one HP Vista and one Dell Win 2000. Most of the time I can open Network Neighborhood or whatever, and they all show up. No problem with transferring files between them. Sometimes - too often - the other computers just don't show up. I'm connected with a 2Wire gateway.
Any clues about this?