windows 7 crash when i use the MS17-010 vulnerability

i am a beginner in hacking (or pentesting) and i have created a virtual machine with windows 7 integral on it to test metasploit and learn how to pentest but when i exploit the MS17-010 (https://www.rapid7.com/db/?type=metasploit) my windows crash i have search in the internet how can i fixed ,i found that i should change de lport (4444) to another random port but it doesnt work the os (windows 7) crashes again