Nathan, this sounds like it can be multiple reasons for the unexpected reboot.
First, are you running a lot of programs at once? You could be experiencing a crash due to the enormous amount of windows or programs running at the same time. Try to run fewer programs at a time.
If this doesn't change anything, you might want to consider additional RAM to your decide to increase performance. Having extra random access for your laptop will provide extra support when your decide has various programs opened at once. With more RAM, your system will be able sustain big files or programs.
Good luck, Nathan.