help! Keep getting emacs locked up / not responding to c-g / having to kill process

[unfrostedpoptart]

This is related to my previous post about clearing the kill ring.  I have a 
frequent case, when running shell buffers, where selecting a lot of the buffer 
(could be thousands of lines) seems to lock up emacs.  Most of the time, one or 
more c-g hits will stop what it was doing and give me back control.  However, 
lately (including 15 minutes ago) I've been hitting this and c-g does nothing 
and ps shows emacs at around 95% cpu.  As this is a shared server, that doesn't 
make me popular with other users!

I end up having to kill the process. This really sucks since I had about a 
dozen shell buffers logged into  multiple servers and running long jobs that 
were all killed when I killed emacs.

Any suggestions on stopping this from happening in the first place and/or 
something stronger than c-g but short of killing emacs?

FYI, this is 24.3.something on REH 5.something.

Thanks!

 David