corrupted MAC error using scp

[Gerhard Magnus]

I'm at my wits end with this problem:

A small LAN with three boxes and hardwired ethernet connections through
a router.
PuteF: server, running FC15 (x86) and LXDE  
PuteB: running FC13 (386) and gnome
PuteD: running FC15 (386) and KDE

I can transfer files between PuteB and PuteD using scp without any
problems. Regardless of which machine the scp is initiated on, all file
transfers between PuteF and PuteB, and between PuteF and PuteD fail with
the error message "Corrupted MAC on input. Disconnecting: Packet
corrupt. lost connection." The time this takes to happen varies within a
few minutes.

Based my not getting this error for file transfers between PuteB and
PuteD (running FC13 and FC15, respectively) I assumed (1) the problem is
with PuteF or its connectivity, and (2) the problem does not involve
different versions of Fedora. Based on what I read on the Web about this
error I assumed the hardware was at fault. So I put in a new ethernet
card on PuteF and connected it to the router with a new cable. But I
still get the "Corrupted MAC" error.