Q:

Session freezes when using the screen command

This happens to me once every couple of hours.  When I use the screen command and attempt to switch between windows by pressing ctrl+shift+a twice in succession, my session freezes.
This has happened to me when I've used putty to ssh to cloud servers and also to servers in my LAN at home.
Does anyone know any fixes to this?

A:

By default C-A A does nothing. Do you have it bound to something in your .screenrc?
The only key combo I've had freeze my screen session is C-a s, which according to the screen manual does "xoff". I've never intentionally hit this combo. I used to blame it on screen freezing until I caught myself hitting C-a s instead of C-a a or C-a A.
Once you've hit that dastardly combo, the only graceful way out is to switch xoff to xon by using the key combo C-a q. Reading through the man page, it all has something to do with flow control. Near as I can tell it emulates Scroll Lock.
Read more about flow control in Gnu's Screen: manual

A:

I don't know about typing Ctrl-A twice, but Ctrl-a A should give a prompt to enter a new title for the current window.  You might want to try Ctrl-q then Ctrl-d a couple of times until you see [Screen is terminating].  If you get that, then nothing has frozen, it was just waiting for input somewhere.  What does your ~/.screenrc file look like, if you have one?

