We have similar problem. But it is typically one employees computer that crashes the most. Although, the other 4 have done the same thing usually only 1 time a week on average. There is no error code, just says it must abort then shuts down. There were days it would crash every 30 mins. Since running repairs it only happens 3-4x a day. 

To try to fix it I have removed/reinstalled QB. I have cleaned our server computer. I have ran fix tools. Nothing seems to help prevent this from happened.