I've never had an issue with the Mediastation crashing. I did have a lockup a few times but that was with a very early OS when I was running multiple VST's in conjunction with lots of FX. I was running enough programs and FX to cause any system to crash so I couldn't fault the MS for it. As anyone who uses lots of VST's knows some can be extremely CPU hungry so when loading a new VST you never know just how power hungry its going to be until your actually using it.
FWIW... I've had more crashes and lockups from my Yamaha 9000 Pro than I've had with all except my early Emulator II.