It's not the most non-techie friendly application, but if you open Spotlight and type 'Console', you'll open it.
Next time a crash occurs, open Console, and under 'All Messages', copy everything that happened a minute or two before the crash. Post it here.
To copy them, use Cmd to select the first one and last one, go to Edit -> Copy, then paste it in here.
If a Crash Report window opens up, copy and paste the error text from that here. That's actually a bit more useful than the Console output, because that shows things directly related to the crash.