Sometimes, right after I submit a computation-intensive run to R in ESS, my whole screen freezes. When that happens, none of the Emacs commands work (I use laptop running XP). My crude solution is to press Control-Alt-Del, go to the Task Manager, and kill the R process, not the Emacs process. (I actually use Process Explorer). Once I kill the R process, I get the Emacs buffers back, but lose the R session. I can then do Meta-R and start again.
Does anyone know of a more graceful way to exit/abort from R within ESS?
Control-G will get you control of emacs again. Then control-C twice will interrupt R and probably get your prompt back.