"remote end hung up unexpectedly"

Be patient with me, it's my first day on git... I like it better than svn already, but I need a bit of help.

After cloning a remote repository, I wanted to update (rebase) an existing remote branch to get the latest master commits, so I switched to it using git checkout, then did a "git merge origin/master" and it updated my local copy so it looked reasonable... I have changes to add to this branch, but I wanted a proper base, so I did a "git commit" and a "git push". The push gave me the above message.

I've checked ssh access (don't have shell) to the other side, my PK is set up.

What went wrong? How can I diagnose it further (-v doesn't help)

I understand that to add my further changes, I should set up a local branch to track this updated remote branch. But I'm assuming that the rebase must be done while switched to the remote branch...?

Clifford Heath.