IBM did successfully enter and even define the PC market.
Microsoft saw the threat of the Internet, and reacted swiftly to own it with Windows 95. Internet Explorer demolished Netscape, with illegal methods, but most people at the time also recognized IE as the better browser. Microsoft also got a strong foothold on mobile with WinCE/PocketPC/Windows Mobile.
Google was an early entrance in social with Orkut, dominating some important emerging markets (Brazil, India).
In each case the companies seemed to lose interest and refocus on their moneymaker divisions. It might be intrinsic to large companies: If you want to advance, you should work where the money is made. So the best and most ambitious people would go there, leaving the forward looking parts of the company to die of negligence.