Apple MacOS and Microsoft Windows are both insecure.
Most of the computers in use on the Internet today are running operating systems that do not protect the system as a whole from any misbehaving application program. System crashes are one manifestation of this problem.
More insidiously, this insecure OS architecture allows viruses and other malevolent programs free reign once they're running.
Don't take programs from strangers!
Take all of this together and you have a situation very like a nuclear power plant: very useful, but the consequences of a failure are very, very dangerous. This is why nuclear power is (supposedly) a very tightly regulated industry.
Educate everyone about this issue - forewarned is forearmed.
This is known in the industry as making a site that "gracefully degrades" to match the capabilities of the user's web browser, and when properly done, this design discipline makes the web site's content accessible to the widest audience.
Petition Apple Computer and Microsoft to rewrite their operating systems so that application programs cannot crash the systems they run on.
We have our work cut out for us.