I've had my new Garmin 66st for just over a month now and really like it...when it isn't crashing!     I check for updates very often and it is running 3.1 and all the latest optional updates, including the chipset.   But, it experiences a "soft crash" about once every hour.  This is usually during a "Find" operation.  The screen slowly fades away and then I have to turn the unit back on.  Very annoying, but not too serious.   Much worse are the "hard crashes".  Yes