Filezilla will not connect

[fullofhope]

Hello forum members
A strange problem.
I've got two desktop computers, although they are in fact on the floor, one by my left foot the other by my right foot, good for kicking them occasionally.
Both are ethernet cabled into my wireless modem. Both have Mageia 3 installed from the same DVD within the last few days. Both have multiple partitions and several OS's. Both have Filezilla as part of the OS. I've configured them both identically. The left won't connect with the right, and the right won't connect with the left. Yes, the firewalls are both turned off.
Now the strange bit. On the right-hand computer I also have PCLinux on another partition. With Mageia on the left and PCLinux on the right, then the left connects perfectly with the right !!! (Though still not the right with the left.)
So what gives? Very obviously nothing wrong in any hardware sense. How can just changing the OS on the right hand side make such a mission-critical difference? They all ping each other perfectly.
Any non-technical hints much appreciated.

[doktor5000]

Please check viewtopic.php?f=8&t=4987