can't network xp computers

I have a home network with 3 computers running xp home. They all seem to
have the same settings yet only 1 of 3 is accessible. All 3 are visible via
"my network places" yet only computer#1 allows the others to access its
files. I've enabled file and print sharing on all 3 and disabled the windows
firewall but still no luck. All computers can access computer#1. When
trying to access computer#2 a message pops up "computer is unaccessible".
When trying to access computer#3 you get a "guest log-in screen" asking for a
password (there are no passwords).
I can't choose to log on under a different user since the "guest" option is
greyed out and therefore my only choice.