network sharing problem with xp pro

I have three computers on a network. One has XP Pro, tne others have XP Home.
All have sp 3. I can access both XP Home computers from XP Pro, but I
cannot access XP Pro from either xp home computers. I can also access either
xp home from the other xp home.
I can ping all computers from each other and local ping. I can see all
shared folders on each machine.
I have all fire walls disabled.
I get the folling message when trying to access xp pro
"computer" is not accessible. You might not have permission to use this
network recource. Contact......
Not enough server storage is available to process this command.
I have increased the Stack size in the xp pro to 15.
Everyone is listed as access to these folders under security.
Use simple file sharing is not chesked on xp pro, but is not visible on xp
home so I assume it is using simple file sharing.
I have read most of the suggestions on this board and others and nothing
seems to work. What am I doing wrong?

--
frustrated