Hi and welcome to the Forum!
It's unusual that it shuts down by itself, when you say a soft reset is this by way of holding the power and home buttons down simultaneously until the Apple logo appears?
Crashing would normally suggest an app is acting funky or a lack of ram, do you close your apps completely regularly?
From the home screen do the four finger swipe up or double press the home button to reveal your multi task bar. These are all the apps that you have opened at one time. Long press an app until it jiggles and a red minus sign will appear above it. Press the minus sign, this will close the app, not delete it, close all your apps, now press the home button to return to your screen. It's a good idea to do this regularly as it helps the iPad run smoothly. Apps that are left open all use bits of ram, so if you have a lot of them open it can cause crashing problems.
Do you have a lot of location services running as they all use ram also, keep these to a minimum. It's also a good idea to clear out your History and Cookies in Safari occasionally as these all save little bits of ram also. Settings - Safari - Clear History and Cookies, if you press the advanced tab here first and then Website Data then Show all Sites you will see all the sites you have been on Safari and all this can add up, so clear history and cookies and start fresh.
All these steps are just general housekeeping for your iPad to run smoothly, do these and let us know how your iPad goes.
iPad 2 3G 64gb