Connection issue between Macs.

[old-wiz]

I have a 24" iMac 2.8 C2D, 2 gb ram, running latest 10.5.8, plus an iBook 1.33ghz PPC G4 running 10.5.8, plus a MBP (recent) running 10.5.8 plus all updates.

The issue:
On the iMac I see the iBook and MBP in shared computers and am able to connect to both and transfer files both ways, no problem. However, on both iBook and MBP I see the iMac in shared computers, but attempts to connect result in "connect failed". The logins are the same on all 3 computers and the password is also the same. The iMac connects very quickly to both the iBook and MBP, but when I try to connect to the iMac from either laptop, it takes a long time then fails.

All 3 systems have file sharing set ON for share via AFP, and none have firewall setup.

Anybody have any suggestions?

 

[old-wiz]

an update..

Found that both the MBP and iBook can connect to each other with no problems.
The only issue is connecting the MBP or iBook to the iMac.

 

[old-wiz]

Another Update

Hmm... Looked in system preferences on the iMac, and "firewall" is greyed out and can't be selected, so I suspect something got screwed up with the firewall so that incoming connections are refused. However, I have no idea how to fix it. Any suggestions??