It means that your computer was trying to run scripts and bad things happened.
Many web pages, including this one, run script code. There are different types including Javascripts, CGI, PHP, Perl, and Ajax to name a few. Those that code the scripts don't always do so in a proper way.
In fact, I was sitting next to a PostgreSQL developer on my way back to Japan last month and he was a big Apple fan. He explained that the reason the Safari browser doesn't load a lot of sites is because it only runs "clean" script code. In fact, about 7-10 MB of coding inside the Firefox and IE browsers is devoted to handling poorly written script code. The advantage is that they run more, the disadvantage is that they can crash and they are also more cumbersome than Safari is.