@ kn
I didn't experience problems the first month of usage.
My troubles started after I left the console on for the night to download GBs worth of demos and performed a system software upgrade, the next day I played these demos. And the first crash happened with Gears of War the next day.
I have no worries keeping my PS3 on for the night to do some folding, but I wouldn't recommend the same for the XBox 360.