To help, we miss some rather obvious information:
Version of LR?
OS and version?
If you're using LR6 / CC 2015 try to deactivate the GPU acceleration - as a quick search in the forum would have returned: Adobe Photoshop Lightroom Help | Lightroom Graphics Processor Acceleration (GPU) Troubleshooting & FAQ
You have some type of problem with your computer. Could be memory or hard drive related or some other hardware problem. Could even be software related, other than LR.
There are millions and millions of people using LR everyday without any problems. So it isn't LR that is crashing. It is something in your computer that is causing LR to crash.