login to remote system using ssh fails

[Geoffrey Leach]

This is Fedora 11, openssh-clients-5.2p1-2.fc11.i586
Same problem happened once before on a Fedora 10 installation; I'm 
ashamed to say that I did not note the solution.

The remote system is F10; same as before.

Two systems are connected via wireless. Connection is good. Previously, 
ssh -l user sys prompted for password and connected. Today (after 
wakeup from hibernate), ssh complained about the remote system's key. 
This has happened before and was always resolvable by removing the old 
entry in .ssh/known_hosts and trying again.

The problem is that now, after entering user's pw, I find that I'm 
logged in to the originating system.

Shutdown, power off/on, reboot does not affect the problem.

Nothing from dmesg.

Any help would be appreciated.