Well I have discovered that rewinding live TV only a few seconds after I start watching a channel (such that it is read from the hard disc, and no longer live) prevents crashing, and I can watch TV in LMCE all day.
This is bizzare... what is the difference!?! - 'live tv' is recorded and read the same as tv that was recorded a few seconds before being read, right??
I have yet to install the latest LMCE update, so i'm not sure if this problem has been fixed...