Remote PC accessible by ssh, scp/rsync not working (anymore)

Remote PC accessible by ssh, scp/rsync not working (anymore)

I have got a remote machine running ubuntu 12.04 LTS. I have used it lots
of times to log in to via ssh and to copy files to via scp and rsync.
Today I was able to log in via ssh, but I am not able to copy stuff to the
remote drives using scp and rsync. I get the following answers:
scp: ssh: connect to host xxx.xxx.xxx.xxx port 22: Operation timed out
rsync: ssh: connect to host xxx.xxx.xxx.xxx port 22: Operation timed out
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: unexplained error (code 255) at
/SourceCache/rsync/rsync-42/rsync/io.c(452) [sender=2.6.9]
What I tried so far: updating and dist-upgrading my machine rebooting my
machine restarting the ssh-deamon (sudo service ssh restart)
What else can I do?
Thanks, Vincent