The PC and internet fuled the productivity gains of the nineties. If you look at the timing, the stock market crashed a couple of months after the ruling came out. Up until that time, the internet was the wild west. With the Microsoft judgment, it became clear to the market that the internet would be subject to regular rules. The stock market plays off such psychological factors. Also, Microsoft was the biggest player back then so it was a blow to the entire industry. People were wondering if the interet boom was a speculative bubble, and the ruling was the pin that popped it.

They weren't. Computers and Internet became a commodity so the market was overcrowded and overhyped. Once the realization happened, the market plummeted and tons of investment and effort went down the drain.

People went batshit insane over the internet in a few years, invested tons and tons and it all collapsed.